i dont understand why ppl nearly dont play ffa games....one of the things i find interesting here is to have multiple enemies and trying to manage the complexity of the situation

Some people clearly do like it, and there's a fair amount of interest in playing it.

It's not as popular as 1v1 and 2v2 for the same reason that it's not part of a ladder, in my opinion. It's hard to measure skill when you can't control the outcome of the game. The worst players can gang up on the best, such that the best would rarely, if ever, win.

Imagine the Impaller in a random 4 player ffa. Can you honestly say that all three of the other players would not attack him until he died, before going after each other?

FFA is a lot of fun for friend to play, or casually, but it hurts when it comes to competative games.

TDoB nailed it.. personally I prefer FFA games, just like I prefer auto dist games on most maps.. but it's not an adequate show of gameplay skill, and too often becomes a game of diplomacy