They're too much of a crutch in PVP. They allow for rubber-band healing and create endless 1v1 battles because resource return is too strong with potions.

Edit: After reading many of the posts in this thread, I thought it helpful to add the following into this first post to help clarify and give further justification for my reasoning:

I think a potion nerf should be strongly considered, and there's past precedent that ZOS wants to reduce rubber-band healing and strong sustain (Templar major mending nerf and Morrowind sustain nerfs).

My request for potion nerfs in PVP simply takes ZOS' past stances on rubber-band healing and resource management further. During the Templar major mending nerf, ZOS took an anti-rubber-band healing stance, and used it as justification for the nerf. If ZOS really wants to cut down on rubber-band healing, then I think potion nerfs are the next logical step, as some potions offer boosts that strengthen healing enough to make rubber-banding possible on non-healing focused builds. I think builds are a bit too strong to begin with, especially when we can hit extremely hard and heal extremely well at the same time, WITHOUT potions. Adding potions to the mix makes the build a bit absurd because we're not sacrificing damage for healing.

Morrowind sustain nerfs were largely about forcing players to make a choice between damage and sustain. The major recovery buffs that last for the majority of a potion cooldown period push that choice more towards damage without experiencing a sustain drought, or on the flip side, even further into sustain that creates endless battles, which is why I see potions as a crutch.

It's quite apparent that the most vocal people in this thread are against the idea of a potion nerf, but I haven't read anything yet that changes my mind about potions being the next logical nerf to get closer to achieving ZOS' desire to reduce rubber-band healing and sustain.