The RPG's and Grenades are fine, there's always a good advance warning. The underbarrel spam though... Died to it three times CONSECUTIVELY in the last game I played. Wouldn't mind seeing it reduced a bit.
I feel like you get more explosives coming your way if you play the commander, sniper or machinegunner classes but that's just a theory...
I don't like being bombed from the air when I'm inside a building that we are capturing. It's just silly, there is just not much (if anything?) you can do about it. I rarely die from bullets, it's usually some random ass bombs that kills me, seems bit over the top.
in multiplayer it seems grenade throws are usually more luck a lot of the time as you sort of just throw in the general direction, where as the bots seem to have a pretty good idea where to place their grenades, and are quite accurate as well.
That being said it makes sense to utilize your grenades and explosives all the time as they are obviously effective.