Maybe (surely) the EU could be restructured to be even more democratic, but isn't that also true for pretty much every country in the world?
Like personally I would like if you could, at both national and EU level, but the fact that you can't isn't a specific failure of the EU.
1. National governments do not have control. That implies that for each government, they could ensure the outcome they wanted, which is impossible in a shared legal system. In the era of the veto, you could argue that they had at least the very minimal level of control over change (by stopping it), but the EU has been systematically removing national vetos.
2. Even when vetos did exist, they were hardly 'control' as a regular person would understand it. That would be akin to arguing that as long as a car has a working brake you're in control even if you can't move the steering wheel or stop the engine.
3. We don't actually know the national governments control who becomes EU Commission President. We believe this to be the case because in theory the treaties say that's how it works, but the EU routinely violates its own treaties. For example the treaties say that the Commission gets Commissioners allocated and the national governments control those assignments. In practice the former president (Juncker) boasted in public that he vetoed any commissioner he didn't like. This is not allowed under the treaties but, happens anyway.
4. The actual process by which vDL became President is entirely and completely opaque. The national leaders walked into a locked room and ... something happened. Then vDL was announced as leader. How was that decision arrived at? Which countries voted for her or against her, and why? Was there even a vote at all? Are leaders being threatened or bought? The question may sound absurd but actually the EU has quite bad problems with corruption, and effectively buying support via massive subsidies to poorer countries is a core tactic.
The point is, nobody can answer these questions because the EU is completely opaque. vDL refusing to release critical negotiations in direct violation of EU law is entirely expected from this system; the EU has lots of laws and regulations but they are always ignored the moment they become inconvenient. No system that claims to be democratic can tolerate such levels of opacity.
One last point. The assumption in your argument above is that if voters elect a politician they will actually represent the people who elected them. At the individual / leadership level it is fairly well known that the EU routinely corrupts politicians into going against voter's wishes by offering to hire them into the Commission temporarily after they lose elections. These jobs come with absolutely massive "pensions" that are well out of line with any normal pension, which require virtually no work to obtain, which can be claimed before reaching retirement age and which can be rescinded if the recipient is disloyal! In effect these so-called "pensions" are legal bribes.
The extent of the pension bribes problem can be seen in the scale of EU payments to UK politicians (who of course all became strong remain supporters):
https://www.armstrongeconomics.com/international-news/europe...
"Democracy is the worst form of government - except for all the others that have been tried". I would suggest the same holds for most of the variations, no system will keep all the people happy (or be perfect).
Personally I am prefer the grander bargains of democracy; transparency (vs back room deals), rule of law (vs corruption), and accountability (vs protection by / for the party). I also would prefer rationality over tribalism, but I suspect that might be too much to ask of humanity.
"Look at Brexit, it has caused economic harm to the UK, and this has caused support for it to drop"
Economic harm?! The impact of Brexit, if any exists at all, is unmeasurable because it's lost in the noise compared to lockdowns and trying to fight COVID.
What we can say for sure is that the people who claimed voting to leave would trigger an immediate recession were wrong. The economy grew in the years after the vote. Actual implementation was largely put on hold just months after leaving due to COVID and little has changed since.
My point is that both systems are fallible and susceptible to both group influence (think peer pressure or the less charitable group think) and the influence of special interests; both good and bad.
As to economic harm, it is measurable and has been measured; even the Bank of England says that the UK will suffer more than other G7 and EU nations due to the current supply side inflation. The World Bank, the IMF, and many maket research firms have said very similar things based on economic data (FDI, trade flows, GDP, etc). If you want to eat a jam doughnut with extra cream and sprinkles, great, own it. Just don't be surprised if someone mentions that it isn't as good for you as a stick of celery. Sticking your fingers in your ears so that you don't need to listen to people telling you otherwise doesn't mean a doughnut is a stick of celery.
People get confused about this because her predecessor Juncker supposedly got the job for this reason; in reality this was a ploy by well-connected EU insiders to make Juncker specifically President, and this rule has not been applied previously or since and likely wouldn't have been if some other party bloc backing some other candidate won instead.
"you lament that EU commissioners are voted in by party blocs in the EU parliament"
Where did I say that? I said the opposite, right? That in theory they are appointed directly by national governments without EU parliament or Commission involvement (in theory, but apparently not in practice). EU Parliament can only fire the entire Commission at once, it doesn't select Commissioners and never has.
"you say that people vote for parties in the UK (they don't they vote for MPs, regardless of their party affiliation is written on the ballot), and that this is good"
No, because I didn't express any view on whether it's good or not, I described how the system works. Why do you keep putting words in my mouth like that?
"even the Bank of England says that the UK will suffer more than other G7 and EU nations due to the current supply side inflation"
Bank of England, IMF etc said a lot of stuff that turned out to be flat wrong about Brexit in the past. None of these institutions has any credibility. Every single one wanted Brexit not to happen for ideological reasons and created "expert" forecasts on that basis. A former BoE chief even said the entire profession of economics was in crisis, their prediction misses were so bad, and he's right.
At any rate, the more important point is that, again, trying to tease apart inflation due to fighting COVID from inflation due to Brexit is now hopeless. I'm not happy about that. I feel like COVID was a massive distraction and has largely prevented the government capitalizing on Brexit, and it also means we'll never be able to resolve this economic impact debate. The cost of lockdowns, mass testing, travel restrictions etc is so massive that Brexit is a mosquito in comparison.
"Sticking your fingers in your ears so that you don't need to listen to people telling you otherwise doesn't mean a doughnut is a stick of celery"
The people in question aren't neutral bystanders, they very much want certain outcomes (for ideological reasons). Brexit is neither a donut nor celery, it's merely a continuation of the long term trend towards decentralized governance - look at a graph of how many countries exist over time to see this. In such a way it can work out better or worse depending very much on your perspective and values.