I certainly defer to your experience. But don't we have highly mobile high explosive systems (bloopers, RPG and more advanced types of the same weapons) which can accomplish these objectives that would be much lighter to haul around? I'm not arguing with you, I'm just asking.
We do have some good direct and indirect fire weapons out there; The Marine Corps has the SMAW (Shoulder-launched Multipurpose Assault Weapon) and the Army has the Karl Gustav recoilless rifle and both have the latest versions of Light Antiarmor Assault Weapon (LAAW). The Mark 19 40mm grenade launchers are serving well and of course, there are the M203 40mm grenade launchers carried under the barrels of some M-16s too. In Afghanistan and Iraq, I've observed that our troops are using TOW and Javelin antitank missiles as direct fire (line of sight) weapons. The antitank rockets and missiles have a lot of punch and the missiles in particular are very precise but the price tag per shot is huge too - about a $150K to a quarter million per trigger pull (they are meant to kill tanks) - so you don't get many of them. You should also have 60mm mortars(Marines), 81mm, and 120mm mortars (Marines and Army) too and they are very, very effective as long as you locate a target well and they'll clear them to be fired for you. They are all wonderful but they all have limitations. Rockets and missiles and mortar rounds are expensive and can be overkill, since anyone standing nearby not involved in the fight will be obliterated too in all likelihood. 40mm grenade launchers are really small mortars and while really good for shaking out hidden enemies in cover, the fragments are small and getting a lethal hit requires a very close hit to make them leak enough.
The .50 shoots very, very flat, penetrates any and all cover, hits exactly where you want it to and scare the blank out of the intended recipients. Because it is accurate and very steady, a good gunner can pinpoint the enemy firing positions and wipe them out without risking anyone on either side of your aiming point. Best of all, it will reach out a mile or more - far further than the missiles and rockets - and still have enough punch left to get bad guys hiding behind walls.
It's a great gun and well worth the trouble of moving them and their ammo cans around.