OK - I know we are cutting it close, but we are just about to retire our 10.8 server and move to 11.5, but I think this change was made in the 10.8>10.9 jump.
In 10,8 when you added a WMS you could rename the layers

In 10.9 and above you don't get that.
Is this behaviour as designed or am I missing something here?
Cheers
ACM