Not a very good idea in my opinion. Even though it is cheap, being able to get weapons a little cheaper, isn't really a bad thing. Not everyone likes the game to be impossible you know.
Also, it would be stupid to take out, because alot of the time when I am playing single player, I use the perks to my advantage, so I can get guns more quickly, for less money. This helps me a lot when I am playing single player, and I am leveling my perks.
So overall no, but maybe, just maybe, in multiplayer they could do that. But even then, I would still be aganst it.