Monkey grip isn't even close to resembling overpowered. 'I constantly power attack for two points, and in return I get crippled on my magic item rewards', and exotic weapon proficiency is identical in that 'I get slightly more powerful in return for being crippled in the possible magic item rewards I can get'.
The only reason one would ever pick up the feats is for concept, or if you were picking up a particularly common exotic weapon like the bastard sword or spiked chain (not that the former is worth it anyway), or if you were small sized and wished to use medium weapons, etc.
Edit: Also, in that build (the traits and flaws are all ridiculously unbalanced), you don't even need monkey grip, you could wield a colossal weapon without it, you want a EWP (Heavy fullblade) instead so your damage actually becomes 12d8. If you're going for super broken, do it right man!
I feel dumb now, I talked about as if you were calling monkey grip overpowered and I apologize.