They're trying to cater to a lot of pro players and make halo 5 prominent in the esports scene. Any drop in accuracy that's not extremely clear and apparent would work against that agenda. I'm sure it could have been considered but probably didn't get too far.

As far as ground pound you pretty much have to land right on them to kill them. Also it allows you to see your spartan do something bad ass. I think it's in line with assassination animations. If you want to go for a big one hit kill they're going to make you trade off a large chunk of time where you lose mobility. To fill that time you get to see a bad ass kill or see yourself totally flub it and then panic.