I actually liked the long cooldown on the heal spell as it made me approach each battle in a more tactical sense.
With a shorter cooldown I could have easily just sent my allies to auto attack 'x' target until a fight was over since anyone with excessive aggro would be thrown a heal.
However due to the long cooldown it made me utilize the tactics menu and player roles much more attentively. For example in the Ogre fight I would set Bethany to heal only the tank Aveline, since I would ensure Aveline used taunt whenever a melee character engaged an ally in combat, keeping most aggro on her. I would then take out any (as a 2h warrior) of the Darkspawn adds when they entered the battlefield, grouping them to ensure maximum AOE damage and keeping my character away from the Ogre AOE.
Using this technique Aveline was easily able to tank the Ogre while I picked off the additional groups, since she received exclusive heals to keep her standing (in this time frame she can easily use two heals if necessary). Once I had dispatched the darkspawn I then joined her in killing the Ogre.
If heal had a much shorter cooldown that fight would have devolved into an extremely simple slash-a-thon since there would be much less emphasis on unwanted aggro if heals could be thrown to multiple characters.
Just my two-cents