I wonder if Star Trek TAS could have been good?

Really the only good animated program put out by Filmation. Roddenberry helmed the show, using the animation aspect to enhance the program within the Filmation budget. It's available for viewing on CBS.com.

I've only seen a few episodes, but it held true to the original series.

I've only seen one- the episode this screenshot came from, The Ambergris Element. And honestly, I admit that I liked it- I liked it despite the clunky and stiff animation and CHEKOV ISN'T IN THE ANIMATED SERIES EXCUSE ME
I have also seen clips of other episodes, and honestly, just by looking at those clips I wonder what the hell Roddenberry was thinking. Those clips alone, man. I felt like I was on some monstrosity of an acid trip. But maybe I'm being too hard on a cartoon series that was made far before I was even born and probably had a limited budget.
That's not to say, though, that I don't appreciate the series at all. It may be... Uh, strange, but there's something kind of charming about it.

I was not a happy camper when I discovered ST:TOS was finally pulled. Like TV Guide and other magazines said at the time, Trek fans were starving for more after the cancelation, and would accept almost anything. Considering Filmation was the worst production company in animation, so bad they even low balled writing, that ST:TAS was as good as it was is surprising.

I was born in 2001, long after all of this, so I'm not sure if I really have a place in judging stuff that existed long before me. I mean, I've absolutely fallen in love with Star Trek as a whole, though I'm currently on the second season of the original series.
But, honestly, the animated series. I'm torn between being fascinated by it's strangeness and wanting to avoid it for the same reason. I mean, I know TAS was made way before I was born, so the technology they had at the time to make these things could possibly appear lame to me.
Honestly, though, I kind of pride myself in being able to appreciate things like this that are older than me and produced using different means. I don't hate TAS, I just think it's kind of strange.

ST:TAS, had a lot of things going against it: lousy animation, lackluster support from the network that couldn't figure out how it survived, and of course, Action For Children's Television, a parents group that tried to destroy childhood by prohibiting violence while making every program educational.

Best comparison I can give you would be to read all of the Robert Heinlein SF stories, or just one, that was serialized in Boys Life magazine. Then read the actual novel he wrote the the comic strips were based on. The BL stories were good, but with so few panels available, were limited.

I can identify with your apprehension. I got a set of old SF shows from the 40s (movie serials) up to the 60s. One in particular, Space Angel, was a childhood (preschool) fave. Watching them today is wild.