Now that I have actual Free Time that does not need to be taken up by worrying about what I should be doing instead of what I actually am doing, I am burrowing through my anime collection to rewatch the shows I keep meaning to rewatch. This is because if I don't take advantage of this now, I may never be able to do so, and my anime collection ceases to be of any use other than as collectors themselves, this time of dust.
It's also a good way to realign my memories of what I remember an anime to be with what it actually is. I rediscover things that I've forgotten, both good and bad, and the results can be surprising. For some reason soundtracks tend to be easier on the ears on older anime, compared to the somewhat forgettable BGMs of many (but not all) anime today. This could be sample bias at work, of course: the fact that I own these anime to be able to rewatch (and have not, say, given them away) means that they have some quality which makes them Worth Having, and good music might as well be one of them. After all, newer anime which I also own on DVD (Lucky Star, The Melancholy of Haruhi Suzumiya) also have great soundtracks.
In terms of character designs and plots, I… don't see much difference, honestly. Advances in animation have let studios tell flashier stories, yes, but that's just fluff. For what really matters, I don't see any hidden and common trait to older anime which makes them inherently superior to newer ones. If it's good, it's good. If not, it's not.
Again, though, this could be sample bias. I may not be seeing much difference in, say, the amount of moe-ness, because I only collect anime which have a given amount of moe anyway: my gateway anime was Ranma 1/2, and my gateway manga was Love Hina, so I know what I like.
Nostalgia tends to exaggerate emotions and opinions in odd ways. This has also convinced me that anyone who says that anime is unconditionally So Much Better Way Back When has no idea what they are talking about.