Some suggestions

[Addah]

I hope when you respond to these suggestions you judge each idea on its own merits. If you express your disapproval I will followup with my own thinking and try to change your mind based on what you said.


Nightmare vs Hell XP rate (not drops)
It would benefit new players if Nightmare had the same XP rate (not drop rate) as Hell, because they would be less dependent on the kindness of strangers boosting them with inf/hell cows. It provides them some independence with leveling up, and only a new member might sacrifice the Hell drop rates to gain more XP early-game if they can't kill anything in Hell difficulty.

Potions upon Death
A little tweak that would be cool is if potions can remain in your belt when you die, so you don't need to re-apply them everytime or pick up the ones you dropped.

Runeword Skill variables
Increasing variability in runewords would help keep end-game players engaged in attempting to craft perfect items. Particularly with skill bonuses, Call to Arms for example, instead of 1-6 variable skills in BO/BC it could be 1-9.
Aside from just the skills, the aura level could have increased variability, for example with Infinity's Conviction aura, from 10-15 up to 10-19 perhaps, but tweaking aura's might be too far.