I think a number of feats & classes from 3.5e should be considered for NWN:EE.
I certainly don't wish to disrupt compatibility but a number of changes and additions to NWN 2 were a welcome change to me such as the feat Able Learner which allows you to invest skill points into skills outside your class with 1 skill point instead of 2, there is many I could list but I'll keep it to a few Practiced Spellcaster, Extra Slot, Greater Weapon Focus & Specialisation, Augmented Healing, Augmented Summing.
As for Classes there are some pretty interesting ones, Mystic Theurge, Arcane Hierophant, Frenzied Berserker, Red Wizard and many others.
I don't wanna go on to much but these are just a few examples and I don't think all of them are necessary but many are great options to spice things up a bit.
Oh and can we fix the Pale Master so you actually get spell progression?