Flaws can really help make for interesting characters. However, the only time they really get used properly is if the player likes using them.
For me, I like personality flaws, things that shape the way my character acts and reacts. I even once had a character who treated a talent as if it were a curse.
However, as the other pointed out, all too often players will take flaws to get the bonuses, and then ignore said flaws during play. Flaw systems that give things like DPs become a tool of power-gamers, and they reinforce power-gaming in players who normally are not power-gamers (because if they don't, they will have problems keeping up with those in their group who do).
ICE will not be introducing any sort of flaw system into RMC, at least not within the foreseeable future.