I'm mostly talking about governance. The biggest "users" and governance decision makers of any PoS protocol will be regulated financial institutions (e.g. Coinbase) operating on behalf of end users. In theory Joe Schmoe can be a staker from his garage, but in practice the only stakers that matter will be regulated custodians (full disclosure, I am the CEO of a regulated custodian) other than a handful of independent ETH whales (like yourself).
Yes there will be a number of custodians "competing" with each other, but they will all largely operate under the same regulatory jurisdiction (or at least cooperating jurisdictions). If a PoS currency becomes mainstream, the Federal Reserve (because regulated banks will be the largest custodians) and Dept. of Treasury will have significant influence on governance debates.
The big issue here is that governance decisions in PoW systems are split between miners (geographically distributed), custodians (largely US based) and other economic actors. In PoS systems only custodians will call the shots. That has very serious implications because custodians are regulated financial institutions with significant network effects, miners do not have this centralizing force.
Lastly, to actually become a miner in a PoS system requires you to find or create a cheap source of energy and hardware and maintain this advantage in perpetuity. This is external to the system and can be done without paying off any existing Bitcoin actor. In a PoS system you, by definition, need to pay to play - you must purchase a sufficient stake of the currency from an existing insider if you want to have a seat at the table. It's the perfect insider game. Some may argue it aligns incentives, but it also centralizes control.
These systems all have different tradeoffs. Maybe some people are ok with these tradeoffs for switching to PoS, but I'm not.