I mean.. we grow teeth a total of 3 times. The first for our baby teeth, the second time for our 'mature' teeth, and the make up 'wisdom' teeth to fill any that might've fallen out at that point. I'm guessing those three growths were the most needed for humans early survival before we got all fancy with farming and hygiene. At which point we kind of broke survival of the fittest and things just kind of happen now.
Kind of like how humans are one of a handful of mammals that didn't evolve out of menstruation.