It feels like you're both coming at this from opposite ends of the same point.

A more helpful and grounded way to look at this is to look at how the value of slamming every last GCD diminishes slightly when our dots carry more of our potency per tick vs our nuke.

Here's a couple of super basic timelines, the first potency is the complete potency so far over the timeline, the potency in brackets is dot damage only. 10 GCDs total, We're going to miss the 5th and 7th GCDs with a heal on both occasions.

Example A: What we have now - 290 Nuke, 70 Dot - 3310 potency over 10 perfect GCDs

1 - Dot - 70
2 - Nuke - 430 (140)
3 - Nuke - 790 (210)
4 - Nuke - 1150 (280)
5 - Heal - 1220 (350)
6 - Nuke - 1580 (420)
7 - Heal - 1650 (490)
8 - Nuke - 2010 (560)
9 - Nuke - 2370 (630)
10 - Nuke - 2730 (700)

Example B: 210 Potency Nuke, 140 Dot - 3290 potency over 10 perfect GCDs

1 - Dot - 140
2 - Nuke - 490 (280)
3 - Nuke - 840 (420)
4 - Nuke - 1190 (560)
5 - Heal - 1330 (700)
6 - Nuke - 1680 (840)
7 - Heal - 1820 (980)
8 - Nuke - 2170 (1120)
9 - Nuke - 2520 (1260)
10 - Nuke - 2870 (1400)

It's super simplified but hopefully it gets the point across. Example B has 20 less peak potency in a target dummy style setting, but yet comes out 140 potency ahead in the end with 2 GCDs missed. The more GCDs you miss, the more example B pulls ahead.

More emphasis on dot damage over nuke damage absolutely raises the skill floor for healer DPS and makes using GCDs for something other than a nuke less 'wasteful'. SE are absolutely missing a trick by not taking one of the healers down this route. Load them up with dots, add a 2.0 Bane style cooldown for good measure and you've got something that'll feel legitimately different for very little work.