Blind-fight In the games I've played in concelment doesn't come into effect that often and their are a lot of spells which can help you with some of the same things the feat helps with, so it just doesn't seem worth spending a feat on. In a different game it could easily be good, but you don't need to provide the best of reasons to vote for a feat.
Improved Grapple: It just doesn't seem that useful. If your trying to grapple a mage to keep him from casting spells and your a fighter type your grapple bonus is already going to be good enougth. If your being grappled by any of the numerous monsters with abilities based on grapple, this feat probally wouldn't help as monsters tend to have insane grapple bonuses.