I don't care if someone's A-List or B-List, if they can do the part the best, that's who should have the part.
Besides, Abrams wants that curious "moviegoer off the street" to want to see his movie, imagine a public thinking "Hmm, Mark Wahlberg as Captain Kirk...maybe Star Trek isn't so nerdy after all"...if his being in it puts fannys in movie seats and makes money, isn't that what Paramount wants most? Remember, the studio doesn't want what we want from Star Trek, Paramount wants to make money. Plain and simple.
Don't forget movie star Genvieve Bujold was the original Captain Janeway on Voyager...and Lloyd Bridges, who was already a tv star at the time, was one of those in consideration for the part of Captain Kirk back in the day.
I wasn't saying anything about STXI being targeted at CHiPS fans...