Yea, the second option is more consumer friendly in general...
I hate this next bit because I always end up coming across as a bit of an asshole, but... I don't really care what's considered the most user friendly option, I care only about how I like things as they are currently (i.e. friendly to one particular user... me). I would much rather force PC players to use a joypad in a potential Halo 5 port, then to introduce mouselook to the game. I don't really view m+kb in the same fashion as I do stuff like racing wheels or arcade sticks. In both of those cases I feel a joypad player has roughly the same potential performance as the other control options (maybe not for Project Cars, heh).. but for kb+m vs controller, I feel that even a mediocre player with a kb+m is likely to run a train on a much higher skilled joypad user, necessitating the two be separated. It just goes against unified nature of the XBL community imo... where you'll start considering what control types players use before you invite them to your games, etc.
I do think leaving it in the dev's hands would likely work out for the best in general... but I'm less convinced about the users.
What I mean "in the users hands" is that if a dev allows both kb/m and controller and gives the option to the user if they would like to play against 1 or both, that there should be a preference that the user would always take.