Well, KERS has the same problems. If everyone gets the same, then someone will use KERS (or P2P or whatever) and the one ahead will use it to, thus making no difference at all.
If the DRS was also available for the guy ahead, then what would be the point of the DRS? We’ve seen when the leader is about to lap someone, that once both cars activate DRS, they hardly get closer.
The whole idea of the P2P or DRS is to make it easier for overtaking, not for defending. It’s a lame addition in its own right, as it doesn’t fix the problem at all, it’s just covering the sun with one finger. And it’s not fair either.
But if free DRS (or P2P) for everyone makes no difference, then better scrap it. Though, at least DRS is designed by the teams (the effectiveness of it varies from team to team), whereas P2P is just the same system, same boost for everyone.