To be fair, the Triple Changer gimmick is still good, even today. To have what is essentially three toys in one is no mean feat, and a triumph of toy engineering that they even resemble what they're supposed to. The problem with them came with the fiction. How? Why? When? These questions didn't really get answered until the Dreamwave comics came around and told us that they were mostly Shockwave's experiments. In the cartoon, they just appeared from nowhere. Even then, the writers didn't seem to know what to do with them, especially Astrotrain. So they fixated on two particualr words; carries cargo. That's pretty much what he did. The only two episode where Astrotrain seemed to have something other to do than carry cargo were 'The God Gambit' where he seems quite imposing, and 'Triple Takeover' where he seems to think that normal run-of-the-mill trains can actually hear him. Not good.
As for Astrotrain himself, I demand more fiction. And a bigger toy. I demand both of these things. Don't get me to set Astrotrain and his massive gang of Intercity 125s on you.