They certainly add character and might be a nice piece to add to the back story after a grievous wound. They do impose some rather stark penalties though.
Yes, perhaps, but remember, not every character has to be good with every skill, and it's rare for a character to even be trained in every skill, so you could choose a penalty that wouldn't affect your character's skill too much. And, these are Paragon tier feats, remember, so a -2 will not be that drastic, but the extra +2 could be enough boost your skill to +20 or so.
I searched for the update earlier. Looks like WotC decided to make MM automatic again like earlier editions. I'm not sure 2+Int is the same as earlier versions.