Healing Assist

As a dedicated healer there's nothing more frustrating then over healing, its a waste of MP, time, and in most case's, causes avoidable damage by staying in AOE areas to cast a heal that was unneeded. That said most of the time, if you know your class, over healing can almost always be avoided... almost.
The point I'm trying to make is that it would be very beneficial and i think quite simple to implement a sub targeting on the party list, which shows to whom a caster is trying to cast a spell on.
It doesn't have to show that "healer A is blue, Healer B is green" but just one color that shows that someone in the party other than yourself has targeted this person.
This way you know who the other healer is targeting and don't waste vital ability cool downs on that same target.
Do you think they will ever do something like this? it doesn't really seem that hard to implement and in my opinion it will really help with MP management and put a bit less stress on healers while raiding.

Raid healers are normally coordinated, due to VoIP or a long run of stints together. I don't think this can become implemented

1.) because the main healer job is reaction based , yeah you might over heal but WHM is meant to see damage and replenish it

2.) I've yet to run a instance where over healing causes a wipe other than spamming medica with regen up and pulling agg by unexpirenced players.

The only vital heal cool down I can see you speaking of is benediction as everything else is rotated throughout fights anyways

The Idea is very simple and other MMOs do that or at least interface add-ons for about a decade now.
Just change the group member's background color in the group frame to green if someone is casting a healing spell on them - done.