Yoshida mentioned in an interview that they get conflicting requests going both ways. Some players are adamant that they want healers to focus on healing and others want healers to have full on DPS rotations. In a separate interview, Yoshida mentioned that designing healers presented a particular challenge/barrier in that they couldn't really replace older healer abilities. They always had to add some new tool. I believe this is because healer toolkits are introduced to counter particular mechanics from different expansions and raid tiers. As a result, they can't just replace them without having to retest whatever they add against the mechanic the old ability was built to address. Additionally, this means its hard to make room on the UI for DPS abilities because they'd be replacing cooldowns meant to address something.
So, according to Yoshida,
1. The healer community is totally divided on the direction of healing jobs.
2. The healer toolkit is a backlog of abilities designed to address different boss mechanics introduced during each expansion.
Given what Yoshida said, I'd posit that if healers were rebuilt with DPS rotations we'd be in a scenario where healers are no longer built for the game they exist in (other than the current expansion). All the older raid content would have mechanics that the healers no longer have cooldowns to deal with because those were sacrificed to make room for DPS. They'd have to test four entirely new jobs against all the existing content just to do that. That's not to say we can't have quality of life improvements. Having the ability to designate two targets for card mechanics so we don't have to target swap on astrologian would be great. A one, two, three rotation could also work if they gave us the ability to cast while moving kind of like in PvP. Or just have the rotation built into one button. At least it would be visually different.