Probably isn't a great reason to take it (USMLE). You can get licensed with the COMLEX everywhere. It is possible to be licensed via USMLE pathway (I did) but pretty unusual from what I gather. This route will probably give you trouble in getting licensed in a very few states (like the "big 5") unless you take the COMLEX as well.
I took the USMLE route because I had already taken I/II. COMLEX at the time was only offered on certain dates in certain places which would have made it very difficult for me to schedule during my intern year when I really wanted to get it out of the way during an elective month when I had a little time to study. Now I believe its on computer so logistically easier tos chedule and take. Might come back to haunt me but I doubt it since I have an unrestricted license in the state where I plan to live.
