Well, to me he reminds the path that Bradly Cooper did at the start of his career. From secondary characters in comedies, he got bigger roles and became an average Hollywood star. So I think at some point at the past you could've ask the same question about Cooper as well, in many cases being considered a star is just a matter of perception and PR. Not sure what path Powell will take and where he will end, but he did participate in writing this movie, so he can take the lead role if he wants.

I agree, there is not a lot of comedy or laughing in this movie, although some of Hit Man characters were quite funny, and the ending a bit too simple. Both appear to be borderline psychopaths, not sure they would just turn to be a suburban couple with kids without having some darker side. Plus, it would be hard for them to explain their relationships if they stay in the same city. But these are minor details, I did like the movie in general. I think it was very well written with interesting plot, although it could've been a bit shorter. And Powell did a good job overall, I think he is a decent actor. Not sure why you didn't find this movie interesting, I would guess it's a matter of what your personally consider as interesting.