It won't and shouldn't have a fighters AB, but the enormous amount of other differences and advantages they have should make up for it. If a monk had a fighters equivalent AB, they'd have to miss out in other ways, not least being that incredibly potent Spell Resistance, their excellent saves, mobility, and AC, all of which are better than a fighters, as well as having a much higher number of attacks per round. Giving it the same BAB as a fighter is a rather ridiculous request considering that the monk is superior in all four of those categories, and the BAB is the 'only' thing the fighter has over the monk. There were quite a few buffs to monks in previous updates, I'm not sure this is really quite necessary.