Sounds to me like someone hasn't been paying much attention when I do expand on why it's bad design, and then proceeds to take that explanation as a personal attack for some reason.
A cooldown-based RPG is one that finds itself somewhere between traditional turn-based combat and real time combat. In real time combat gameplay, there are a functionally limitless amount of ways that a player can engage with any given encounter, because there are so many factors that can change from one run of that fight to the next. Even when just looking at the player, your movement, your positioning, your choice of attacks and abilities, your timing, your ability to dodge or block incoming enemy attacks... All of that creates a countless number of pathways to victory, and there's not truly a "right" answer. This creates an environment where you have to make choices at any given moment about how you're going to proceed, and that is the cornerstone of combat in video games--it's what makes games fun and interesting. Let's take a look at some examples from Kingdom Hearts. Here are three different versions of a fight with one of the game's superbosses, Xion:
Clear 1: First Clear
Clear 2: Style Clear
Clear 3: Speed Clear
Each player from these examples approached the fight differently, had different experiences, and achieved victory regardless. That dynamism is what makes that game charming and fun. It's what draws may people in and keeps them there. None of those are the "right" answer. All of them won.
A cooldown-based RPG lacks nearly all of the factors that a real time combat game can take advantage of, and to add to that, it's very slow. You are only allowed to perform so many actions in a given window of time, so it needs to find a different solution to create the same cornerstone experience of looking at your options and making a choice, or it risks turning off its audience. It does this by providing to the player a library of abilities to pick from at any given moment, and by creating dynamic interactions between those abilities, that sense of choice and decision-making can be achieved. While it's true that XIV is very linear in its rotation design, that does not mean it is inherently devoid of those choices. And for most jobs, their "neutral" state is something that requires some level of focus to perform correctly. Moreover, it's important if you are going to create a wide selection of abilities, that the majority of them are well-catered to the game you've created. Having situational tools is not a bad thing, but the majority of abilities you provide to the player should feel like viable options for the majority of your game.
The current healer design fails to accomplish any of the above descriptions. It fails to offer a neutral with any sort of required focus or attention, and there is a severely inconsistent appeal to choice that occurs within the healer's gameplay. How much you need your actual healing is not a consistent factor in this game. In a savage fight, I might use each of them at some point, but most of the time, I only need two to three. As a Sage, I find that in almost all forms of content, the only healing I actually require is Kerachole and Ixochole plus the free healing from Kardia. There are vastly more situations in which I use only those two heals and nothing else than there are situations where I need anything else. It would be like if, in those Kingdom Hearts examples, everything except for my ability to attack, guard, dodge, and cast Cure was taken away. Only that would still provide a more engaging gameplay experience than healers currently provide.
That is bad game design. You can love it all you want, but it is still bad design. All I'm asking for is the option to have a proper gameplay experience with any of the four healers. I don't need to take away your ability to button mash, I just want the option to do more than that.