Depends very much on the region you plan to visit (
), e.g. in french nature reserves sometimes tents are only allowed next to the hut whereas in other conuntries' national parks camping is forbidden at all.
I wonder wheter overcrowded huts are the normal -- except some very highly frequented huts you nearly always will find place; a phonecall for reservation more and more becomes obligatory.
So if you look for tranquility and nature bring your tent; for going light it is dispensable.