"It has always been so" is kind of implied in the complaint that feats have never been a good fit. Tying Dragonmark growth to level is one of several issues I've had with Dragonmarks as feats. My biggest issue is that feats have almost always represented some sort of character choice; to train, to gain new knowledge or skill. You never choose to manifest a Dragonmark. Dragonmarks choose you, based on fickle whims of prophecy. Now I don't know about you, but when I think "fickle whim of prophecy", I think "DM Fiat" much more than "feats".