No one’s mentioned the biggest improvement in all the enhanced editions. Unlike the originals, they’re consistently playable in Windows 10.
Making these titles run on modern machines is a time consuming pain in the ass, at best! For the technologically inept and people who are paranoid about downloading stuff from random websites, it can be damn near impossible.
Very relevant example: I recently spent maybe an hour trying to make NWN start on my 64 bit Windows 10 machine, at which point I quit and played something else.
I’m sure it’s easier if you have the patience/knowhow to set up a virtual machine running XP, but the enhanced editions are so people can pay extra for the convenience of having the game run with the click of a button.
Everything else, every minor improvement to the graphics or the UI, every bug fix, every piece of new or restored content, that’s all just gravy. Enhanced edition really just means Windows 10 and mobile compatible edition.