Cure wounds is on more spell lists than Healing word, so there is a point to both. But the practical problem is that healing would have to be 3 times greater than DPR for it to be a viable strategy beyond keeping people from bleeding out, because that's how the action economy works out.
In some cases, it actually is. By DPR, you can't just take the average dice, you have to adjust the enemy's to-hit with the healing target's AC. Or save vs save DC.
So, let's say you have a party consisting of a wizard, the cleric (you), and a barbarian. Let's say you're all fighting an Ogre and everyone in your team is down 15 hp. Well, if the wizard has mage armor up, they'd probably have 15 AC by level 2. You're a knowledge cleric for no reason other than to have your AC at 18. Your Barbarian has an AC of 15 and decided to rage and reckless attack.
Which one should you heal, and when?
Well, at your wizard, he'll do 8.25 DPR. At you, he'll do 6.3. However, at the Barbarian, he does 5.89 DPR.
This is interesting, because the average for a CW is likely to be 7.5 HP. Meanwhile, the likely HPR for HW would be 5.5, less than the average damage the barbarian would take. That means, you're likely to buy the barbarian 2 rounds of combat with CW while buying only 1 (maybe none if the ogre's turn is next anyways) with HW.
This goes into the effective HP of the fights and the impact of this effective HP. A heal is much more valuable on a martial, period, because martials usually have ways to mitigate damage like Rage, Evasion, BA dodges and high AC. They're more likely to boost the effectiveness of the healing than a spellcaster like a wizard or sorcerer. You can throw buffs on to increase this effectiveness as well, something like shield of faith.
I'm not sure you need 3x the enemy's DPR for a heal to be worth it, so long as it buys the martial more than one turn of time, it may be fine. The DPR drop of a martial like a barbarian going down could be around 11.415 against that Ogre. In a way, that heal was an indirect vehicle to prevent damage from falling 11.415. It does depend on turn order, but since you might buy the barbarian 2 turns, you can spend an extra turn contributing to the battle in more meaningful ways than your cantrips. Might give you room to cast Bless or Bane or Command.