Well if you are the FO in a party you should just use them since it's the best benefit for everyone. It's weird to let a lv15 or 20 sdjz class buff and debuff when you have your lv30s. It's just common sense.
I'm also not lumping everyone together, I just seen more people that don't do it then doing it. It should just be second nature to a FO that first thing you do is buff and debuff and heal your party where needed before supporting with spell locking or freezing etc.