I have...a ton of 80s. But I'm not sure forcing everyone to go through level 1 to 85 is the answer. You don't really gain all that much. Your rotations are largely static. And you certainly don't need much skill to PVE level grind (I once knew a DK who did 250 dps at level 80, i mean how the heck do you go through 25 levels doing that bad?).

I think we over-complicate situations. Eddie Merckx, famous cyclist, said his training was to 'bike lots'. Similiarly, the best way to be good at arena is to do arena, the best way to do BGs is to do them. It doesn't matter what the level is to some extent. Yes you'll get new tricks, and gearing at 80 is a whole different ball game, but the principles are the same.

Just like group play. Do you need to go through 20 different dungeons throughout your leveling 'career' before you know how to group play? Would that even help? No, i doubt it. Everything is faceroll. Its not until either 1) the player becomes interested in how to actually play properly, or 2) the content gets too difficult for facerolling, that you have any sort of 'hey I can play better in a group'. Otherwise it's 'meh' and 'shrug'. The reason people suck is because they got through 80 levels without having a need to not suck. This will not change if its 10 levels or whatever.