How about reducing respawn timers on monsters in all zones released prior to Seekers of Adoulin to 5 minutes or less?

It's easier/faster than ever to get from level 1 to 99 and even the most casual players are running around in item level 117 gear, so it doesn't make any sense to have to wait 10-15 mins, and in some cases even longer, for monsters in older zones to respawn. Is there any practical reason as to why such a change wouldn't/shouldn't happen?