The monk is a front line combat character. All other front line fighters have d10 HD, why doesn't the monk? Is the monk supposed to be a "support" fighter? As a front line fighter they should also have the best BAB.
The monk has one main purpose, to do melee damage. Yes they get nifty abilities here and there, but giving them d10 HD and good BAB would not in any way imbalance them, when you compare them to fighters who get a lot of feats.
Although many monk builds are around agility and avoiding getting hit -- those are only to compensate for the fact that they wear no armor.
They are constantly over shadowed by the weapon weilding fighter -- whose weapons will in the very least be masterwork, but will usually be magical and eventually have special weapon properties that do even more damage. Giving the monk the good BAB still would not make them better that a fighter but would give them a better shot at being more balanced with the other fighting classes, and would give them a better chance at executing combat maneuvers.
Paizo please give the monk the 10 HD and good BAB they deserve.
Hrmm... apparently there is a whole thread about this that I have not seen before...