To be honest, the reason I don't want to use citext and lower(), is me
being lazy. If I have to use these features, there is more work for me
converting from SQL Server to Postgresql. I have to make more changes to my
database, and more to my software.
But, developers are generally lazy, so you could argue that this reason is
"compelling".
The other reason, is that I assume that "lower()" adds overhead, so makes
things slower than they need to be.
Whether that is true, and if that is a compelling reason, I don't know.
Marcel