Currencies are used to purchase things. If the purchasing power of 1 BTC changes dramatically, it matters.
I also need water to live my life, but that doesn't make me feel the need to price everything in gallons of water.
Buy bitcoin at $1 on Jan 1, sell at $10 on dec 31. I now owe taxes on $9 in gains, so I’ll need USD$3 on April 15. If on Jan 2, I buy more Bitcoin at $10 and it drops to $6 on April 15 that will suck because then I’ll need to sell half my Bitcoin to pay taxes.
I'm long on crypto myself, but come on. This crash still affects the prices of goods and services, unless all you're buying is other crypto and nothing else. We are nowhere near the point where shops don't assume they have to check the bitcoin/usd cost every few minutes to adjust their pricing.