Why don't you as a player experience all the "real content" before firing your mouth off?

The main strength of a WHM is the extremely potent AoE healing and better "on demand" ST healing (Embrace + Physick will end up healing more in the long run, but in FF14, damages to the tanks are spiky, and you cannot rely on Embrace + Physick to heal those spike damages, and Lustrates are limited, A WHM's Cure II can handle these damages easily).

"Oh but there's no content in this game that requires so much healing bla bla bla", and that is why the current Meta for raid healing is as follows:
WHM is the main healer in raid groups while being supplemented with the Scholar's fairy and occasional Lustrates.
Scholar spends most of their time DPSing, only switching to heal mode to assist the WHM in certain heal intensive phases.

A WHM's healing capability is extremely powerful, he/she does not require much from his/her co-healer (Embraces and occasional Lustrates as stated above) in order to keep the tank healthy.

If your team is not utilizing the Meta above, it's similar to people insist Monks perform raid mechanics instead of continually punching the boss, and then complain "Monks suck, their dps are the worst" as the poor monk's stacks keep falling off due to mechanic handling.

I started my essay with OP bashing, but based on his lodestone, it is pretty clear that he has not done any "real content" that requires the healers to have at least half a brain intact to clear. If you're in any way familiar with the current state of end game in FF14, you would not run your mouth stating "herp derp whm is so useless".

We'll continue on with the "Astro will replace WHMs!!" argument, as soon as SE releases more info such as additional skills etc for the class, any "theory crafting" done now is just baseless ASSumption.