Spam is going to be a big issue on nostr. Would you rather have to deal with it when people other than early adopters are trying to use Nostr and giving up due to the volume of spam?

Abuse of the network is probably going to be the biggest challenge for public relays imo.

It wasn't a particularly sophisticated attack, and pretty annoying, it could have also been run privately. However, it's definitely raised the issue of just how sensitive the protocol is to spammers.