Idea #1
Make lightwell something to "top" everyone's health. Something like a renew but instead of being cast on a single player, it's cast on an area. And every tick heals the player with the least health. And make it have 10 ticks or so.
Idea #2
Make lightwell a temporary heal buff. Something like increasing healing done to raid members within 10yd of the lightwell by 10%.
Idea #3
Make light well sort of a beacon. Il'l explain.
Lightwell 1m Cooldown
Creates a Holy Lightwell. Healing done to the lightwell is increased by 100%. When the lightwell is healed it heals the 5 closest raid members for 20% of the healing done.
There's so much shit you can do with lightwell... Blizzard is just lazy (or doesn't think it's important).