Let me name a few examples.
1. chrome.scripting API and the concept of "isolated worlds" is easier to use and understand than what we had before.
2. Dynamic content scripts registration that everyone has waited for so long.
3. userScripts API is also a welcome addition. It does not provide everything and it needs to be improved, but it is already a good step forward. Finally the existence of userscript managers was recognized by Chrome and they're trying to make life easier for them.
Also, the bug fixes. Before the expansion of the extensions platform team there were major bugs that could be open for many years, and now I see them closing one by one. To an outside observer it may look ridiculous that there was such a problem from the start, but that's how underinvestment looks like and I am happy that the situation improves.
Even DNR is not a bad API by itself, the problem that was never addressed is that in MV3 there is no blocking webRequest anymore and DNR cannot fully replace it.
edit: formatting