I so agree with this. I think the starkest difference is between the Spiderman movies. MJ was basically just an ornament for Peter to pine over, she was beautiful, Peter was smarter, stronger, funnier, everything-er. As much as ASM2 annoyed me, throughout those two movies Gwen was smarter than Peter, she was funny, she got in the way because not only was she trying to help, she was actually succeeding at helping because she was a better scientist than Peter. The creepy way both relationships are started notwithstanding, Gwen is pretty much an example of a lead/love interest. Being a love interest is a trait of her character, not its defining characteristic.
I think that with Leslie being a fellow crime-fighter (albeit in a different way) is what makes her more likeable, she's a person beyond Jim. Barbara is a hot mess, and both Jim and Montoya are better off without her. (I'm a few episodes behind, so I'm not completely sure what's up with that.)
As for an earlier comment bringing Batman's relationships in as an example of how this is just the way comic relationships are: Batman is a notoriously emotionally stunted individual. He is pretty much supposed to be an example of what not to do in matters of the heart. Vicki Vale was the closest thing to a well balanced love interest he had, beyond that Selena is messed up as hell and Talia is mostly evil (which is why Batman usually doesn't actually pursue those romantic possibilities, at least in the older stories, I don't read new 52. He only really engaged Catwoman after she turned full hero.)