Good point.
Such a suit, once a mature technology would have some amazing advantages. Tacticaly, it could bring weapons traditionaly reserved for crew-served or vehicle/aircraft use down to "alley level". It would be the same quantum leap in urban combat capabilites just as when the 20mm cannon, and anti-tank guns were deployed in urban combat in a flexible fashion in WWII...
However, unless it could move and jump very, very, fast, (Just like the MI Marauder suits in Starship Troopers did) the suit would also be a "bullet magnet".
And since the major threat in the current conflict comes from IED's often capable of taking out armored vehicles. I don't know how well they'd play out in unconventional warfare. (in "conventional" mixed infantry/armor engagments against an enemy that does not have powered armor, it could well be devastating, IMO..)
If powered armor comes to pass, I think it'll be the "F-22" of the infantry. A very formidable next generation weapons system, but possibly already obsolete, just as it's coming on line. Just like for the F-22, the UCAV writing is on the wall. It's not a matter of "if", but "when".
For ground combat, I forsee similar developments as the UCAV. Not just Remote controled guns and vehicles, but swarms of atonomous "Crabs" and "birds" that work in concert like mobile intelligent minefields. Unless you could field an enormous amount of suited troops, these disposable bots would swarm them.