You say you're ADDING new features to make game-play just right? Adding = taking things away? I apologize if I missed the memo on that one.
Weapon limits were introduced due to the limitations of console, to make games more accessible to the masses, and for realism in some cases. (Though I'd argue Call of Duty is not realistic.)
Carrying multiple weapons is FUN and allows for more dynamic gameplay and prevents backtracking.
(singleplayer) Prevents getting stuck somewhere and being screwed because all you have is a pea-shooter while your surrounded by tanks.
It's FUN trying to collect every weapon without dieing.
If you REALLY have to limit weapons in some way here is the proper way it should be done:
Limit it to a single weapon per-slot/type, IE:
PIC or Railgun, $500 sniper or Ramjet, Flamethrower or Grenade Launcher, laser rifle or laser chaingun or Tiberium Fanchette Gun, Chem gun or Chem Sprayer, etc...
Even better:
Free repair gun or upgraded repair gun, Officer's rocket launcher or Gunner's Rocket Launcher.
Now THAT would be an upgrade, stopping redundancy when one weapon is an obvious upgrade over another, or perhaps you prefer one of another. (IE: You want the $500 sniper for its instant ballistic velocity and no tracer.)