I would like to see psionics in NWN, that would be nice, BUT I do believe it would have to be implemented as another magetype char.
All the special sence/detect/speak to plants and animals etc. would be very hard to use.
But most of these powers is also available to mage/priest chars in PnP (as spells), so even if they did not implement a psio. they could still make spells that did these things
Indeed the thing I miss the most is NOT ENOUGH SPELLS TO CHOOSE FROM
Note to Kakero : Psionics in Wiz 8 has nothing to do with d&d psio. In wiz 8 it's very combat oriented, and they use the same "manasource" so it was "easy" to make psio. in wiz 8.