GotG is a thing because Thanos is so heavily involved in Cosmic Marvel and it's easier to include at least some of that side somehow rather than cut that entire part of Thanos' background out and still try to make him work. Everyone in Guardians in the comics has major history with Thanos one way or another (you know, like his daughter Gamora) and they can pull the most amount of cosmic characters into a movie about them because they have so many ties to other groups while still keeping it in the general tone of the Avengers. The premise is also weird enough to at least get attention for being out there.

I assume they're just making Ant-Man to make it easier to use Ultron (unless they're really going to use Tony again? But that's so fucking dumb. Don't do that Marvel. Tony Stark can't do everything)

That said, any time they want to start making superheroine movies is fine with me. I don't know why we don't have a Black Widow movie already. Though I'm excited for Guardians in part because it's "female characters who have real roles and do things" quotient seems pretty high compared to the other sausage fests that is MCU. Apart from Thor.