I should've posted on this a while back. I'm going to do my best to respond to the OP, and not to the thread as it has evolved.
If you want to play whm, play it because you like the job and the responsibilities it brings with it. If you play it well, people will always be glad to have you in their parties/alliances/whatever.
Yes, whms are healers. No, whms are not "just" healers.
A whm's job is to keep the party going strong, in as continuous a manner as is possible. That means keeping it alive and healthy, and minimizing downtime if possible.
A good whm can benefit from a refresher, but is not dependent upon one in normal situations. Being able to manage their mp pool well is one of the traits of a good whm. So, yes, refresh is nice. But it really is not addictive.
whms bring things to parties that no one else really can, such as Cure V's, Raise III, Stona, etc. But to my mind, the thing a whm really brings is a focus on the health of the party as a going concern, and the ability to do so, better than any other job. There's also no confusion as to what the whm's role will be, like there can be with other jobs. And I like that.
I've devoted a lot of time trying to be the best whm I can be. Through skilling up, meriting, thoughtful gear selection, etc., I've at least become a powerful whm. I've also become somewhat faster over time. As to whether I'm good... all my efforts don't make me a great whm or even necessarily a good one. I hope that I'm at least a decent one. But what makes me better is not my gear or my merits. What makes me better is caring about my job and about the people I'm with.
If you feel the same way, you'll truly enjoy leveling whm up. If not... lol I can't relate so I couldn't begin to give you advice on alternatives. I've never felt a need or even a strong desire to level up other jobs to a high level.
All the best,
Fire