This is a feature we see wth Salesforce’s Chatter (which I loathe, but have to use from time to time). Basically, full names are included with @clay type mentions by using brackets.
I think the same feature would be really useful for Discourse, potentially as a setting that can be turned on and off by admins. With it on, using @clay would expand in the text to something like @[Clay Heaton].
In our environment, in particular, given that all of the other tools that we use will convert somebody’s username into their full name, it’s a little jarring to see Discourse posts with just @usernames everywhere, and have to think for a minute about who the people are.