We shouldn't be doubling down on bad projects on the sole basis of their existing. Let's look at this neutrally:
Ignoring its limited spending options, since that's what we're deciding whether to change, the Fey Gauge at present...
- Is a builder-spender resource that starts from 0.
- Builds from Aetherflow spenders.
- Is decimal (stacks up to 10 contributions' worth of charge -- i.e., takes until just over 120 seconds into the fight, or about 3 minutes of sustained combat, to charge) but appears centigrade for aesthetic.
Given that, the main consequences of typing additional spenders to the Fey Gauge would be that...
- They all effectively start on cooldown.
- They all compete with each other.
- They may sometimes encourage rushed Aetherflow spending -- likely on Energy Drain.
Put more simply, to tie Fey skills to the Fey Gauge would be to greatly diminish one's use of Fey skills unless met with a plethora of accordant changes.