Well Rangers are as vulnerable Defensewise as Mages in terraria, it shouldnt be like that, ranger armor provides a bit more protection then mage robes. So the Range and Magic helms need a larger defence gap between them.
Well, I use the melee fighter's equipment, and I still manage to use melee, ranged, and magic just fine. It just depends on the situation. If its Skeletron Prime or The Twins, I use Megashark and kill them with relative ease. If its The Destroyer, use Excalibur and slaughter him.
I think this video http://www.youtube.com/watch?v=F67bNc5zMCE&feature=player_embedded easily shows just how powerful magic is, and hence, why it's imperative they have lesser defensive stats than melee. /discussion After seeing that video I feel like melee needs a buff, XD
