J.J Abrams is a massive Star Wars fan, and always has been. He admitted numerous times while making Star Trek that he was a never a big Trek fan growing up, but instead Star Wars fan. He also initially rejected the offer to direct episode 7 because of the pressure/expectations surrounding the final product.
Also, I've never understood the disdain Abrams seems to attract. He's incredibly gifted filmmaker from the technical perspective, with a real eye for blocking scenes and moving the camera. There certainly were problems with Episode 7, but the manner in which the movie flowed from scene to scene, and the cinematography, are not included in that category. Hand him a competent script and Abrams will deliver.
The main reason he accepted the Trek directing job, was because his writing partners presented him with an interesting take on the reboot, and urged Abrams to do it. I'm a huge fan of "Behind the Scenes" film documentaries, and Abrams stated many times he wasn't a massive Trek fan growing up, but instead, a huge Star Wars fan.