Justifying extensions of government power with "but they can already do that" is cowardice at best and disingenuous at worst.
There's of course argument that if it's easier it will do it more often so it costs more. But that's something that will need to be controlled through political system.
Basically development of humanity is making forms of oppression increasingly more painless and predictable to both the oppressor and the oppressed. Predictability and painlessness is good for business so we thrive.
You can't get rid of oppression. Humans will always divide into the ones that hoard power and those who don't with former living off the latter. Best we can do and the best we've actually done is to make this process as painless and as predictable as possible. Currently we are at the stage of territorially divided monopolies on violence. We learned in world wars that "territorially divided" is a very important part.
What kind of opression do you prefer? Filling a tax form every year and paying what you calculated under the threat of arrest (while telling yourself you are voluntarily contributing to society and less fortunate) or being raided by a warband with guns on random intervals taking whatever they please and leaving you only what they at the time believe will let you bounce back so they can raid you again sometime in the future?
Either you are one who enacts or profits from violence or you are affected and robbed by violence. It's a constant setup since the beginning of the human race (or even before that). The only change that evolution of civilization delivers is making the violence predictable and gradual, thus less painfull, thus allowing for more efficient economic activity. If you make oppressors work harder for their cut they'll just take more from you once they do take it.
The main value of democracy is making the oppressed docile and easily subjugated.
And yes, winning election in US is way too costly. Budgets for campaigning should be capped. Other countries manage to sustain democracies with far less. Ultimately it doesn't matter who wins as long as it's not the same faction all the time. In that case unrest wouldn't be suppressed and violence would necessarily get more painful.
Democracy didn't win because it's moral or just. It won because it's most efficient system of maintaining oppression in post industrial technological landscape. You can look at how fragile single party system of China is, or Soviet Union was in comparison to even just rudimentary two party system like in US.