I actually don't think they performed very well. I just look at the EU GDP that's now half the size of the US compared to bigger than US 20 years ago, and at standard of living of middle working class, which has slowly been going downhill in the last 15-20 or so years for a lot of people(worst of all southern europe) and at a more accelerated rate in the last 3-4 years. All due to their decisions and policies and I hold them accountable for it.
Like you don't need the unfair power of hindsight to know that tying your energy independence to Russia (your military adversary and the reason NATO exists) was a bad decision back then, or that staying dependent on US military and tech was bad for sovereignty, or that pursuing unrealistic climate goals was a bad decision, or that opening your borders to millions of unvetted people from unstable regions with high crime and low education was bad, since many people have been saying all these were bad decisions 20 years ago but they were ignored because the gravy train was still running and the EU political elite never game much of a shit about what the peasants though anyway. And now that the gravy train has stopped and the piper has to be paid, our leadership class are trying to gaslight us and deflect the blame for their recklessness at best or just suppress voices of dissent at worst.
And even if we were to assume they performed super well, that doesn't mean I should now swallow tyrannical laws designed to suppress our freedoms while they give themselves exemptions, just because different people from a different era who are no longer in power made some good decisions 30 years ago under the same umbrella of the EU since the EU-EC of today as an org is a vastly different beast than the EU of 30 years ago. There wasn't even a common currency and central bank 30 years ago.