Well, some thoughts from someone currently downrange...
.50 cals on humvees, I have no problems with this. There are an aweful lot of M240Bs and even SAWs mounted, but many combat units are using their .50 cal weapons that normally would be used in a static defensive role on their vehicles. The majority of humvees I see out and about are .50 cal totting. The rest usually belong to combat support type units, psy-ops, medical ATLS, convoy rigs, etc.
TOW missile launchers do not currently fit the up-armored versions of the humvee. On the other hand, CROWS, a computerized target acquisition system with remotely control weapon is being fitted as it becomes available. This weapon system has great thermal optics on board and can see with zooming capabilties.
Mounted recon elements are finding a new niche in occupational roles. LRAS3 sights for long range target acquisition can sopt enemies miles away and allow the scout crew to either relay the position or call in CAS, artillery fires very, very accurately.
BFT devices are fitted to nearly every combat vehicle allowing it so see every other vehicle equipped with a BFT and enemy positions, IEDs, and other items of note on a computerized map. The communication capabilities of American army vehicles is amazing right now with new introductions over the last year.
Delta Force units, CAG, wouldn't be likely to be seen in a game such as BFV as their role is more point raids in urban terrain and counter-terror work. Ranger elements as such normally operate with large Ranger units. A SF ODA team would be a likely unit to see, and my unit ahs worked with them several times on various large scale missions. SF undertakes missions that are very wide ranging from point raids on high value targets, infiltration, ambushes, and lots of other sneaky sneak stuff. They would make an interesting addition to the force.
Small ambush-patol kill teams are all the rage right now. Regular line troopers set up a fire team with a designated marksman or sniper, and basically set ambushes waiting for the enemy to appear. These are special elements, but not special troops as they can come from any line platoon. Using them as a recon/sniping fireteam that is very cheap would be interesting to see.
Javelin anti-tank teams would provide an infantry-based anti-armor asset. The Javelin is an advanced top-taack missile that can pretty much kill anything out there.
Weapons teams fitted with machine guns and loaders would be an interesting way to provide infantry based heavy weapons. Many infantry units keep their heavy weapons in seperate teams dedicated to laying down fire for the rest of the line squads as they assault.
Personally, I would like to see some sort of mounted recon team, like a Shadow without the anti-armor missiles.
The Bradley is a well rounded IFV, not APC. The difference is that an APC brings troops to the fight, and IFV has the firepower to support them and suppress/destroy enemies as the squad advances. Bradleys have always had TOW missiles as part of the design, giving the infantry organic anti-armor assets. With the additions of reactive armor and upgraded commo and sights, the Bradley will remain in service for a long time.
I can't say too much about the Stryker because I have no personal experience with them.
The Army, more than any other branch, has access to specialized units. Helicopter air power from the mobility of UH60 Blackhawks, recon with the OH58 Kiowa Warriors, and killing power with AH64D Apaches.
In addition are the many varied units from air-mobile to airborne to armored.