I'm not nostalgic over Thundercats, I'm nostalgic for an era of TV where networks actually gave a shit and didn't force their artists to pump out a shitty looking promo over the span of a weekend. I fucking miss animation in my animated cartoons.
I'm nostalgic over artists being so beaten down by the system of having to work on shit like Yo Yogi that they turn around and make Rocko's Modern Life because they want to make something they actually enjoy, rather than drinking the Kool-Aid and saying, "The reboot is great... All my friends are working on it!".
I'm nostalgic over the artists in the industry actually being immensely talented, having a firm grasp on drawing fundamentals and quite a bit of animation knowledge, and were given the tools by the networks to develop a cartoon with whatever visual style they want. Now suits with a failing network are cutting budgets while artists who lack the know-how to work around limitations due to being given a show right out of fucking college are baffled on how to make a good cartoon on a $10 budget. It's amazing that the nuPPG looks fucking worse than the old one when the one one was already designed to be cheaply made.
Lastly, I'm nostalgic that cartoons sought out to attract adult (parent) audiences rather than embarrass them and the people who worked on B:TAS or Tiny Toons never felt the need to say in interviews, "We don't care if adult manbabies hate these reboots, they can go somewhere else, this is for kids!".