The modern day cassocks look very refined on the clergy. It looks to me like the fabric used to make them is very expensive and long lasting. I have never seen a wrinkle in them.
In contrast, I would like to see the cassocks worn centuries ago. I imagine the material they used was much more rustic and not so form fitting. But as far as style goes, it has remained about the same for many hundreds of years.
I'm sure the Catholic and other churches, that have a tradition of formalities, will continue to have the clergy wear cassocks for years to come.
The pastor at my church only wears a cassock on special religious days. Otherwise, his clothing is quite informal. I like that.