One of the things I really appreciate about IRC is the raw simplicity of the protocol. I hope that does not get lost in an effort to modernize.
The last time I looked at IRCv3 I was disappointed by how much was an optional extension. My opinion is that a strong 'minimum' protocol is critical to interoperability and opportunities for federated protocols to function well across providers. I recall that was the main, non XML, reason that XMPP failed. Of course I also dislike XML as a data storage / transmission format.
And it makes sense, IRC is already out there and has a ton of servers and clients working, you can't split that community based on the client they're using otherwise you're just creating yet another isolated chat protocol like a ton others before it.