So I'll admit to using it, only in "toy" setups...
I use it with trust and ident, on local connections though, not password....
I try to keep my laptops clean of mysqld, and I use PG. And only on my laptop/PC, I make a database for every user... And every "app" get's a userid, and a schema.... Every user get's passwordless access to their database. And the "userid" associates the app, and the defaults that get used on their connections.
So, I think it's "neat", but wouldn't be put out if it was removed ...