Over the past few patches, we've seen ZoS try to make a push for more widely usable skills and sets, mainly through the use of some, "Scales with your highest offensive stats" function.
For starters, I'd like to say YES, THANK YOU ZOS. I really like the way they're trying to give players more viable options for builds, and the Stamina/Magicka divide is one of the biggest roadblocks to having build diversity. So I'd just like to pitch the idea of going even further with this, and simply putting the two together.

This of course keeps with the theme of player diversity and flexibility, as well as promoting the horizontal progression system we're seeing more of. Additionally however, it would also cut back on all those checks to see which stat is higher, and at this point any calculation we can remove seems like a plus.

The main argument I see arising from this is that it would "dumb down" the game, but I don't believe this would affect the game's complexity at all. Currently, the player doesn't actually get to make a decision regarding how they allocate their damage stats. If you're Stamina-based, you choose Weapon damage/crit/pen. If you're Magicka-based, you chose Spell damage/crit/pen. There's no reason to ever not do this, as any cross-investment just results in less effectiveness overall with no real gain. As it stands, the current split between Weapon and Spell stats just provides the illusion of choice with no actual impact.

By merging these stats, players will gain access to a whole range of new skills to play with, as well as freeing up all those items that currently exist solely to provide a Magicka or Stamina option of an already existing item.

NOTE: In order to keep the effectiveness of the base-game classes' passives, I would add two new buffs to compensate for the loss of Sorcery/Prophecy:
- Illuminate: Now provides a buff increasing party's Penetration stat.
- Exploitation: Now provides a buff increasing party's Max Stats OR Stat Regen.