honestly these are things that sadly do not have impact on kids, unlike something say like Darth Vader being revealed to be Luke's father. as a kid I'm like "ok well Count Dooku is a bad guy and Darth Sidious is a bad guy, so OF course they're on the same side" and of course I didn't give a shit about his politics. They are just bad guys fighting against good guys. But when you look at it as an adult and actually get into Dooku's politics you realize he is a man with a goal and his own ambitions and his own disappointment with the Jedi order so he decided to split. Very autonomous-seeming character, and not necessarily evil. It's like hearing Mace Windu's line about "he used to be a Jedi, he couldn't murder anyone it's not in his character" without having the meta-knowledge "this is Star Wars, so of course there has to be a bad guy". So it is more of a surprise when you find out he's working for someone else. Unfortunately everyone who sees it as a kid will never be able to feel that surprise.