Generators in front of force fields?

a lot of the amerish bases are stupidly, hilariously defensible

(underground nanite systems or whatever it's called, I'm looking at you)

but yeah the idea that towers are less defensible than the new amp stations (or hell, the single-cap-point amp stations) is just

/shrug, I usually don't have a problem getting out (as LA or Infil).. albiet I don't usually go to super camped bases.. so perhaps I don't have the issues you are experiencing.

That being said.. I still do like the tower design (mostly)
My favorite base design philosophy

A Point inside the base, accessible and closest to the spawn room. Not coverable FROM spawn, Vehicles cannot hit or otherwise effect capping the A point in any way shape or form.

B point in a building. Vehicles may not effect the point at all (not able to spam into windows or such). However, the pathway from the defenders spawnpoint TO the B point can be impacted by vehicle gameplay.

C point, furthest away. Heavily impacted by vehicle combat (low or lack of cover, exposed to air) .. and someday perhaps, vehicles can cap this point.

The 2 best bases that do this are:
-Crossroads (albiet the B point is a little too far IMHO), and the C point isn't exposed enough.
-Saerro (again C point not exposed enough, BUT it is far enough away to count.)

I also have no issues getting out of towers... sorta. I mean, if the tower isn't super camped, getting out is easy. If the tower is super camped, chance are the enemy has A point, and your first goal doesn't involve leaving the tower to begin with.

Towers with A point in the tower, and Regent Rock specifically, are the most defensible bases in the game, I find. 15 minutes of Reinforcements Needed will out-zerg all but the most determined assaults.