They are not banned actually because they are being planned for the OICW (I don't know what it's X-number is) with air bursting and explosive rounds to peirce body armor.
And it's also the opinion of a lot of authors and even some "real" military people that like it or not explosive rounds are going to have to come into play to more easily bypass such things as body armor.....and those nagging terrorist types who are so hocked up on drugs you can pump a mag into them and have em still shooting at you heh. Can't do that when you explode
Also 50-cal rifles fire "explosive" rounds.
Now White phospherous (Sp?) rounds were banned because they didn't increase kill they just burned horribly and crippled people in ways that are just not settling thinking about.
As far as "waste of munitions" well as I kind of said "waste of munitions" only counts when you
have munitions if on the other hand you had a weapon with nearly unlimited fire then you wouldn't much care along those lines.
Thats like if you gave me a tank with an endless supply of ammo you can be darned sure I'm shooting every grunt, tank and mean looking rabbit I can with DU rounds hehe.