@OP
It's pretty much what someone else said. Paizo has nailed hit die size and BAB together and refuses to allow them to separate.
I don't really care about the smaller hit die, but a real base attack would be nice.
They've done so much to improve monk since the first iteration, especially with the archtypes, that I feel a little guilty for still being annoyed about it.
I would gladly give up a good save, flurry, stunning fist, and a host of other semi-useful things in exchange for a better BAB. Paizo says no, but they WILL let me give up my entire ki pool and all attached abilities in order to get a +2 to hit with a wisdom check. (Martial Artist - Exploit Weakness)
Meh. -.-
(I should point out that Exploit Weakness has a lot of good things it can do, it's just the bump to your attack that is underwhelming.)