To me having healing spell doesn't necessarily cause a player to spam it indefinitely. There is a cooldown (albeit short). One can run out of mana potions; also one‘s mana pool can be low. So, the argument that healing spell causes a player to spam it indefinitely is invalid.
I enjoy having the healing spell. I didn't spam it. I played the game strategically. Using healing spell was a last resort because they were some other spells that a mage can use to keep the party alive (there's plenty in DA:O. I cannot recall them at present because I haven't played it in a while, and DA II I haven't touched it since I beat it on my mage.).
The thing about Barrier is that it can work. The problem is that a mage has to be solely dedicated to just spam Barrier or she/he will run out of mana, which will leave spamming the limited mana potions that a mage can carry (five for the mages in my game). What Bioware can do is to increase the mana pool of mages, which will allow the mage to be a DPS as well as being a supporting team member.
There is a problem with healing in Dragon Age: Inquisition when one is not in certain areas where there is a cache of healing potions. My Inquisitor is limited to 12 potions. Even though I seldom run out of potions because I have regen potions (six potions for my heroine via a belt, and six for Sera), which makes this new system more viable, but removing healing on the argument that it makes the player invulnerable is absurd. In that case, we can also say the same about Barrier (Guard for Warriors and Rogues). It does the same as healing spell did in previous Dragon Age installments using that argument.
Having healing spell doesn't cause a player to not play strategically. I didn't misuse it. I'm certain some players didn't either. Taking away choices is not the way to go. Dragon Age: Inquisition adapted the slogan play your way. There is a game that allows a player to play her/his way; it is Bethesda's: The Elder Scrolls Online. In that game, my mage can be a tank, heal, sport two-handed weapons, daggers, sword and shield and wear any armor he or she chooses, with the exception if she wears other armor then cloth, her mana pool will suffer. Still, there is a way to circumvent that by investing points into passive skills.
Edit: Knight Enchanter does have a healing spell, but it has a very long cooldown. My statement here is from having Vivienne in my party. That healing spell cannot be used often. Everytime I used Vivienne to heal the party after my potions ran out (that was before my potion limit increased from eight to twelve; 8-12) the cooldown didn't reset; the wholetime I was out with her, the cooldown didn't reset. To me, this displays how much healing spell is idscouraged in Dragon Age: Inquisition. My argument here is: increase the mana pool of mages.