There is one situation when cryptos' value relative to fiat is important. If you live off crypto, and you have no fiat source of income or a buffer for situations like this, when markets are down.

Unfortunately we haven't reached the point when we can have a real crypto economy (or more specifically a STEEM economy), where direct payments in crypto can pay for life expenses whatever they may be. So then, fiat transactions come in, with all their fees and the costs and pain associated with selling crypto when it is down.

Fortunately I am not in this situation. But others are, and I think we've seen their troubles. On the bright side, when crypto prices go back up, they will be the first to rejoice, having all their income in crypto.