This is a really good review, and I love this 2D series. I remember watching it on Cartoon Network back in the day when it released. Also, yeah I think this was where Ventress had her debut as a character.
Yeah, I read the original Thrawn Trilogy and they're great books, it was cool that Timothy Zahn came back to write the rebooted novels with Thrawn, but those originals were great.
It is pretty mad how much story they could cram between the films, but thinking about it, there's 8-10 years or so between Phantom Menace and AOTC, and then maybe another 3 years between that and ROTS, then 17 or so years between that and ANH, 3 or so between that and Empire and another 2 or 3 between that and ROTJ, so there is plenty of room for expansion with books, shows, games and comics.
I think the Sequals missed a chance to do that, considering TFW and TLJ transition instantly with no room for expansion, and kind of the same with the final film. Because of that, they couldn't flesh out characters and add new ones with ease like they could here.
I loved this, and the 3D clone wars is really good too, because like you said, there is so much expansion for characters, I especially love how the clones were given some real personality in the 3D version, compared to how we see them in the films.