The things I'd like to see aren't really moddable probably but maybe Larian will add them later:
Roll for stats at character creation. Point Buy is fine but rolling is a nice option. I've used a CE table to increase stats, but if you want to respec it is undone and has to be done over again
Optional toggle for no crit fail/success on skill checks. There are some mods recently that makes the base a roll a 2 but still allows crit successes. I know there's that one 99 check but I didn't see a difference failing or succeeding it.
Scaling above level 12. There's a mod to provide some of the features past 12 that works well but it doesn't increase proficiency bonus past 4 or sneak attack dice over 6d6. Maybe when the modding tools come out these limitations can be overcome.
Sortable spell bar. Man, I just want my spells to be ordered by level without having to spend a lot of time doing it manually or unpreparing/repreparing the spells in a specific order.
