No... having no level cap in your design document is actually the BETTER system because that would require you to think of a leveling curve and skill system that can HANDLE it.
Not doing this, means you are stuck with whatever level you designed your entire game around. Worse, if you designed your entire game around level progression of some kind (so your game is only balanced when a player sticks EXACTLY to that curve).
This is why Gearbox are bad game designers. This is something you think about BEFORE MAKING THE GAME. And they designed the game so that the level can't be extended. They killed their game by design. And this is why I regretted buying the BL2 season pass. It offers nothing of value (well, for me). And I have the looming feeling DLC4 won't deliver either.