Jetpacks would promote solo play, completely annihilating the concept of this game.
And if you could use a jetpack, who would want to use anything else? Just as in tribes 2, no one uses any other armors except for base raping or maybe defense. If you want to fight at all, you get a light armor and an energy pack, there is simply no other way.
The designers wanted to create a game in which every single combination would have all kinds of uses. Who needs a tank or a reaver to take out opposing armor when someone in a cheap old jetpack could do a better job, buzzing around and tossing rockets?
This game has been very well designed, in my opinion. You COULD go out solo, and get around just fine on your quadbike, and blast a few people before getting run down by a larger group. Or you could join a larger squad, and go off and do something dynamic ^_^
Tribes 2 seems like a pretty horrible comparison to PS to me. All you could do in that game was either cap, or sit on your butt and defend. If you said you were an antivehicle specialist or a demolitions expert, people would just laugh at you and call you a newb
However, there are sooooo many roles to fill in PS, very few people will become adept at them all, and most of the playerbase will be perfectly happy specializing in one role and becoming well known for it. I for one would choose the one MAX pilot that everyone knows and respects over the l33t idiot that comes stomping along and says "OMG OMG I KAN mAXor and HAXXOR and CIRLCE-STRAEF!?@"
