As far as I understand, without any work (energy consumption) that is directly tied to the value of the asset, there's no argument left for it to be a currency, i.e. it can only be categorised as a security asset.
Staking Eth: Investment in common enterprise, expectation of profit and profit derived from others. Looks and quacks like a security.
Buying and holding Eth without staking it shouldn't be considered a security, while staking said Eth should be considered a security. At least if we're still following the "Howey Test".
A different thing is what happens with a liquid staking token like stETH, a much better argument can be made that it quacks and walks like a security.
Besides that important clarification, validators are already receiving income for their efforts. The tips and MEV are already flowing to their wallets as we speak, it's only the issuance that is locked. The particular change required to unlock funds is rather trivial and can be implemented on your own even if you wanted to. But doing so without a large consensus of validators would fork you out of the main chain and those unlocked coins could be rather useless, this should show the delicate balance that decentralized consensus involves.