Yeah, but for people who don't get Bitcoin, there isn't really any way of paying for relays. Most people associate Bitcoin with scammers and are going to stop listening as soon as it is mentioned unfortunately. These people may be interested in freedom of speech or the ability to own your own identity and following, but dismiss nostr because using it required them to also be interested in Bitcoin. 

The same is true for people into crypto. Nostr is a killer for most niche shitcoins because it can do what most token projects try and achieve using Bitcoin, which has better stability and network effect. Bitcoin would naturally come to be used if we allowed a free market. But by insisting on Bitcoin only, we are doing the same thing that shitcoins do, but with Bitcoin. But making clients that can use multiple crypto currencies we would undermine them by exposing to Bitcoins network effect. 

The former group is more important but the second is a good thing to do on principle to demonstrate that nostr doesn't care what monetary unit it uses.