There may also be a regulatory angle here. ETFs that are backed by Bitcoin have been repeatedly smacked down by the SEC, but futures that merely bet on the price while not touching actual Bitcoin seem to be OK. I can imagine that this probably infuriates true believers.

But whither bitcoin, you say? Moving those is easy! Yes, but holding them is hard. Who wants Your Favorite Mutual Fund to hold bitcoins? Not them, that's for sure. There's much more risk there than necessary.

It does if you only want to be exposed to price movements. With futures you can get that exposure with a much lower initial outlay than if you bought (or sold) the underlying. Leverage, in other words.

That's pretty much the point of them. Whether it's something that you'd find value in is somewhat beside the point. As well as speculation, I'd expect there is probably a market for people who actually want to use bitcoin as a medium of exchange. The current price fluctuations are a pain in the arse.