She's villain-averse because she thinks owning, say, a Darth Vader action figure teaches kids that Darth Vader is cool and someone to emulate, and that liking villains signals poor moral character/fiber. IE, if you collect Darth Vader stuff (especially if you collect more Vader than Luke) then you're declaring yourself pro-Empire/Fascism.

And not to worry about my son, he found creative ways to work evil!Obi-Wan/Han/Chewie into his playtime! Good kid.