Quote Originally Posted by HouseRules View Post
It does not matter that bloodline is relatively useless. It is useful because they count as Hit Dice (while not giving any actual hit die, but counts towards skill cap), and Caster Level to all Spellcaster Classes.

Even if bloodline is relatively useless, Mundane is also relatively useless. If you say one, why not the other?
bloodlines progress any class feature you have as if you had a bunch of extra levels in it(but it does not gives you extra class features) so it does not progress only spellcaster level: it would also progress the boost in ac from the monk class feature and a bunch of other things like that.