Onion-
I do agree with you that Cover Scent is not a necessary however it typically will be a critical part of your hunt when the wind is blowing wrong. Even with it the wind can mess your hunt up. Last weekend I got winded by a group of young bucks and I was using scent cover. That of course just shows how true your statement "it depends on the deer" is. But To me it's better to be safe than sorry.
And about scent attractants- they do help but definately aren't needed