From what I understand, if you d/c, rage-quit, plug-pull, the other team gets all the money and spp and you don't get jack except a lower rating on your "reliability" rating. During the beta there was no penalty for just quitting mid-match, but the full version handles that. So, other than being robbed a full game's exp, I don't think you lose much playing in the public leauge. I think it's cool to use to try out different races and f-around.
The cherry-picking has been there since FUMBBL though: "1600 Ork lfg gob/chaos only" - that's always gonna be there. We're busy with our leauges and if we ever get these other guys to get the game, we can have even bigger/longer/harder tourneys going.