There is a base reason tanks are not designed the same way healer are : Tanking abilities need to have some cooldown, while healing ones need to have a solution where there is nothing left. Also, Tanks are physical melee jobs, and base FFXIV design en physical melee jobs is combo. While healer are mage, and mage base design in FFXIV is spam the same spell again and again, and dot. Even the SUM in HW was mostly Ruin spam. A bit less because bio and miasma were on 18 and 24s duration, but after tri-disaster you were going Ruin until bio fade out, and when going for Bahamut transe were Spam Ruin III.

In your exemple, Guard and Wall would be dead/trap actions. Even more dead/trap than Tank stance in SB or current gcd heal actions, while at least, healing GCD is extremely situationnal and mostly something you'ill see in progress/failure recovery than current boss routine.

What it would be nice to do is both reducing healing kits of healer, to make them more reliant of GCD heal, and giving some more engaging DPS tools outside nuke/dot. If they had to do mone thing is giving a more flashy burst phase (we are talking the current state of the game), because the other solution : making bosses hit so hard that healer cannot do anything else than healing is not gonna happened.