If I were to estimate the amount of damage my player has avoided by hitting and running with mobility, I would say it was more than worth the +1 ac and 4hp.Yeah, but that's later. At 4th level +4 hp and +1 AC is far more valuable. And in my experience, Mobile is not a "rare" feat. People do take it. I've seen many monks take it, at 8th level.
Atillia is one of the few chars with odd stats. And "fixing" that is usually a priority.
Just expressing an opinion. Game is going good for me. My "rare" feat is actually an interesting choice I wouldn't normally do (even at 8th or 12th level).