other than the occasional "dammit, i didnt want a stat point there" is there any real reason to reroll

like, getting proficiencies up or something? does it benefit much?

couple things come to mind:

As you said, to raise your profs quicker. Lets say you have a rank1 in something, you need to at least kill level 2 monsters. I suppose you could reroll everytime you get to level 5 and power through those levels quickly to get a few percent prof right away....

You can also reroll in order to get the items your character is wearing into your inventory. (I've done this a few times)

Rerolling also lets you chose a new class as well.

Sometimes I get up to level 5 or 10 and realize that I forgot to put out my starting stats or if I change my mind about what character I'm going to make. It can be useful when you need it but if you don't need it then don't worry about it