The Second and Third Movie took place during the Buu Saga, when Toriyama wrote the manga as a joke. Plus, Goten and Trunks were the main leads as both movies instead of the adults to draw in kids. I'm sure that in more capable hands, Broly would get back at Goku by fucking his wife silly.
A lot of people like Broly because he's the only movie villain aside from Cooler who has a backstory that fit in well with the canon. Plus, he's shown to be strong, requiring four Super Saiyans, or three and half Saiyans to take down as opposed to the usual one Super Saiyan that ever villain after Freeza needs to be put down.