Is Mutants and Masterminds really as versatile as I've heard?

[Michael Tree]

The only change I'd make to M&M would be to break Attack and Defense up into a couple of seperate skills (pistol, rifle, MG, etc for attack and Dodge and Parry for defense).

M&M already can do this for attacks, with feats. The Attack Focus feat gives you +1 to either ranged or melee attacks, but not both. The Attack Specialization feat gives you +2 to a single attack type. If you define each class of weapon as a single attack type, it works well. So essentially attack bonus has three levels of costs:
2 points per +1 to all attacks
1 point per +1 to just ranged or melee attacks
.5 points per +1 to a single type of attack

Defense doesn't really split up this way, but with the Block maneuver you don't really need a specialized parry ability. If you really want, you could create Ranged Defense and Melee Defense feats, which work like the attack focus feat.

I would not recommend making any of them skills. Skills in M&M2e are extremely cheap, add the ability score bonuses to them, and have a much higher cap.