What I would like to see is Constitution health regen benefit both mana and health. Thematically that would make more sense to me. Also, I realize Con is very valuable now as is.
However, I feel like this would allow both melee and mages to better diversify their builds by making INT feel less mandatory for everyone and provide more compelling decisions and thematically CON means you're planning for a longer term. Regen = longer term.
The net result would be an interesting choice where con means to both mages and melee a bit more gas in the tank for fights. Dex is more burst. Primary stat is more damage. Intuitive. Presents more build choices. And could promote longer TTK which I see as an additional bonus.