[jwfiv]

I'm thinking the key word is mobility.

An 80 ton cannon can't get to where it needs to be in order to acquire its target quickly enough.

A bomber or fighter can.

The American 21st Century blitzkrieg will make der Schickelgruber's move across Europe seem cumbersome and slow.

[jdege]

Personally, I rather like the idea of IF systems that move at the same rate as the grunts. That remote-control airplane with all the wiz-bang weaponry won't be there, if the weather is bad, or if some REMF decides that attacking a rock on the other side of the country looks more impressive on the TV cameras, etc.

[USNBandit]

Sustained fire support is hard to provide with aircraft, and that is coming from a fighter guy. Aircraft are good for on call close air support, and messing up the rear of the enemy. Heavy mech needs the support of heavy mobile artillery. The better C3 and fire support you can give to infantry and armor, the less they have to fight. With proper fire support from self propelled artillery, like Crusader and MLRS, our infantry and armor can spend more time directing fire and less time bleeding.