More of the issue is that it's really hard to set up. It's getting better with things like DNSChain, but it's still not exactly something a non-technical person can get going with in 10 minutes. It's also not something you can use on your phone safely yet.

It's not going to be something that legitimate companies are going to use for their primary domain name for a long time. More than that, it's going to be used in niche applications - decentralised identity (id/ rather than u/), primarily, along with being used as a name service for things like OpenBazaar and maybe Tor.

On the other hand, if you happen to run a company or project and have some form of cryptocurrency, you might as well exchange some of that for namecoins and register d/whatever, just in case.