Na i don't think it was an executive decision at all. If anything, it was to me a sign of how gamers are not playing games today they way they used to in the past. Maybe Halo4 did make some mistakes, but it was all by design. One thing that COD has done since COD4 is change the way casuals play games online. And those casuals are the people who made Halo2 huge back in the day. The reason they play COD now is because in that game, everyone can be good. Get a few kills, get a lot of points, call in a UAV, a chopper, a turret, whatever. The game helps the gamer be better at the game and in the end, its an ultimately more gratifying experience to them than Halo is. Get 5 kills, unlock a scope, camo, etc.. its constant "instant gratification" in that game. And it does that very VERY well.
Notice how the huge games all have a lot of "instant gratification" in them now. Thats what 343i tried to do with 4, give more incentive to the people who arent that good at Halo to be good at Halo.