Larian games have a Story Mode difficulty; I have no problem putting an infinite re-roll ability here. Of course, if this is implemented, why not just let people automatically succeed any dialogue check?
Larian games also have an Easy Mode: Maybe all dialogue DCs could be decreased by 5? And/or you get 1 re-roll per check.

Normal or Hard or 5e RAW mode should NOT have infinite re-rolls. If I select a hard difficulty, I don't want to be tempted at every failed check to roll again. That would not be fun for me. If I re-rolled, I would feel like I'm cheating. If I didn't re-roll, I'd feel like I was purposefully missing out on content. Neither is fun (for me).

An "infinite re-roll" should not be present in every game mode. (An optional check-box that is, by default, turned off would also be fine with me)