I support the idea of students being cautiously mentored in poor weather, just to learn how scary it can be. Similarly with strong winds, though that is a skill which really should be mastered. When you actually experience flying in "Special VFR" conditions, you quickly realize that you'd best have everything else going your way, so better plan for it!
In the UK we actually require
better than "ordinary" VFR weather for special VFR flight in controlled airspace.
Go figure, I think you say over there.