I think anyone with any appreciation for animation as an artform wold concede that there wasn't a lot there to appreciate.
You think wrong. I'm a lifelong animation fan, and it's because
of my early love for Filmation's work. Yes, it was limited animation, which was a matter of budgetary necessity, but they did the best they could with the limited resources and techniques at their disposal. Their artwork was better than any of their contemporaries'. Their background paintings were gorgeous and rich, their cel art was clean and slick unlike the sloppier work of a lot of Hanna-Barbera's contemporary output, and their designs for the aliens, ships, and exotic landscapes of TAS were wildly imaginative. There were superb artists working for Filmation; they just had to work within a set of budgetary and logistical limits which were actually quite routine for the industry and the era.
Indeed, many of the creators who elevated TV animation to new heights in the '90s, such as Bruce Timm and Paul Dini, got their starts at Filmation, though that was later than TAS. Lou Scheimer was the Roger Corman of animation, giving many future greats their start in the business.
TAS is remembered for the writing and the fact they got most of the original cast back to do the voices, not because the art was so great.
Absolutely wrong. The art
was fantastic, as good as anything you'd find on TV in the '70s. It just didn't move