Genuine question: Who decides that?

When there is a prominent founder, everyone usually tends to defer to them (in this case, Vitalik, see what happened to ETC vs ETH).

That's was my point. The ability to stake shouldn't be based on an arbitrary and temporary exchange rate. What happens if USD/ETH is $0.0001? $1B? It should still work regardless of the exchange rate.

Current implementation depends on the exchange rate and creates an incentive structure towards centralization.

> Current implementation depends on the exchange rate

No, it does not. You are staking ETH, not USD. Essentially, you are staking a percentage of all ETH, percentage capped from below.

The decision to use 32 ETH was a trade off based on the exchange rate at the time, 32ETH being ~$5k, which the devs thought was enough so that it wouldn’t be cost prohibitive to get involved and hurt enough to stay honest. When the exchange rate changes dramatically, like it did and will in the future, it changes the incentive structure in staking. So, yes, the current implementation’s incentive structures do depend on the exchange rate.

32 ETH wasn't chosen randomly. There is a cost to having too many validators on the network. 32 ETH was chosen to make sure that didn't happen while still being low enough to allow for a lot of validators.

Yeah yeah, everything can always be changed in the future.

Ethereum regularly undergoes hard forks to change its parameters. There's no schelling point over protocol specifics with Ethereum like there is with, say, Bitcoin.