I rewatched Batman TAS lately and it was just as good as I remembered, if a little too short and simple (obviously) when compared with the movies I have since seen.
On the whole I would say cartoons nowadays are a lot more straightforward, especially from Disney. Good guys always good, bad guys start bad but become reformed through the power of friendship. It's really bloody annoying to see the same tired old formula, and if it's not that then it's 'everyone is good, some people are just misguided.' Nonsense.
That said, I do like Kim Possible, mostly because for me it reminds me of the old days of cartoons, as long as I close my eyes when a moral message is being espoused.
Generally I think nostalgia filters out the bad cartoons from our youth, but I think the good ones from the nineties were better than the best ones from today.