When you have to compromise your ideology of fun you start to ask yoursef is it fun anymore.
Separating the xpon from xpoff allows players to pursue what they enjoy about Battleground PvP. If you want to farm undergeared players you risk leveling out (eliminating said twink from bracket). If you want to twink out with your pvp out you can to your hearts content. And if your aim is to just coast through the leveling process (queue for dungeon and bg while questing) with minimal facerolling then you are taken care of as well.
See no compromise on anyone’s part there. The troll will have to start from scratch to grief levelers, the twinks will beable to compete with other twinks and levelers can play as casual as they want without interfering with the experience of the elitists. Win win for all. The trolls might have to put in a little more time to get what they want but no one is denying them the simple pleasures of melting noobs.