Well, you're not wrong! I understand power arbitrage is already a thing and for the most part it's OK. But once in a while you get situations like the crazy contracts in Texas a few years back. And I am a little concerned that if we create a large enough storage market controlled by a few big enough players, they could play financial games with a critical commodity, ie hoarding both generation and storage for peak resale value.
In both situations maybe there's an argument for market efficiencies and liquidity and such. But it scares me a little.
I am not a financial person (in the solar field, but not markets). I could totally be talking outta my ass!