In terms of flavour, it’d be nice, sure… but realistically, the system just isn’t there to support it yet. Adding different accents or whatever means that each NPC type would need all their dialogue options individually redone. This early in the development cycle, when NPCs are still buggy and not fully implemented, you’re essentially building on quicksand. It doesn’t make much sense to go through and write up a half-dozen variations on the dialogue before all the options are solidified; you need to get the basics of what they’re saying down before you can start playing around with how there’s saying it.
Later, when NPCs are more stable, some kind of proper conversation tree system could be implemented, such that there’d be an actual point to chatting up and otherwise dealing with the NPCs. Modding capability is easy enough to include, if it’s made a priority at the time of implementation, so one the devs have an NPC conversation system in a workable state, then anyone could go through and write up whatever accents they like. Until then, anything of this sort that gets done would just have to be redone later… which isn’t really worth the effort for a flavour-type feature.