You are actually using cryptocurrency in the product!
Many CFD sites and listed Futures exchanges provide you the ability to speculate on crypto but specifically do not allow you to do so using cryptocurrency as the margin collateral.
Cryptocurrency cash-settled futures provide a direct use-case for crypto because it requires traders to use the asset itself for cash settlement.
Hodlers never need to sell
Many crypto hodlers do not want to move their coins to an exchange to sell to manage risk.
With crypto Futures you can send a portion of that crypto asset to an exchange to establish a hedge position where you will earn more crypto as the price declines. In financial engineering terms this creates a "synthetic USD" position. Thus, you are doing a perfect USD hedge without touching USD or selling your crypto.
Improved tools to hedge cryptocurrency price risk
How often do you hear people say “x” cryptocurrency is too volatile to do business as a merchant? Well, inverse crypto/USD futures allow you to hedge USD value using only the crypto asset.
This makes holding crypto less risky because you can use it in these vehicles to stabilise in USD value! These products give the opportunity to “smoothen” volatility for merchants who use this argument to avoid crypto. These are risk averse firms who need risk averse solutions to integrate crypto.
More liquidity for crypto markets
Futures and other derivatives allows people to get in and out of crypto more easily since liquidity builds when there are more products allowing traders to use and access them.
Market makers on crypto orderbooks can better manage their exposure if there are Futures available for them to frictionlessly hedge risk in either direction while providing liquidity on underlying spot markets.
This contributes to a virtuous liquidity cycle in crypto markets where a rising tide floats all boats.
Maturing financial market for cryptocurrency
Futures allow the market to anchor their expectations of price into the future. By pricing the asset in different maturities there is a curve that develops, which forms the basis for a "rates" market in crypto assets. This is fundamental to cryptocurrency gaining more credibility as a financial asset.
More efficient price discovery
By allowing investors to easily go short and long, the markets price discovery mechanism is more efficient which could provide for smoother market adjustments rather than jittery market.