because UK DB are even worst

Exactly. People do what gives them the most exp.

Thus, it unbalances the game because people use setups/do things that they wouldn't do in a competitive match to get them more exp; Like let an opponent repair, not save a team mate, etc.

There needs to be a complete reworking of the exp system.

Absolutely. Unfortunately, how do you make an xp model that recognizes honor, self-sacrifice and comradery?

You emphasize winning over all else. In the long run, the more you hurt your team, the less experience per game you earn. The more you help, you get the idea. It's simple and adaptable. If the meta-game changes, you don't need to change XP weights or game code to keep the rewards consistent.

Then the problem is people start focussing on the bad players on their team, and how it's that guy's fault that you got less XP. So you ask for mechanisms to award you more XP even if you lost, since you were at least achieving personal accomplishments... and you end up where we are now.

Lj is right on track. It doesn't make sense to have one style of play that eliminates completely the others.