Because WHM has more consistent options to restore MP. You get to have abilities like Assize on top of that, as well as a free cure 2 spell 15% of the time. The AST is a crit instead, still paying full out, and outside of Lumin Aether, requires me to not only rely on a 1/6 chance on a card, but demands me to use it on myself selfishly instead of spreading something like Balance later on the line.

And as to the comment about the jobs being similar, or having to "make it op to be played," it wasn't needed. People had trouble trusting it thanks to how release was, while people who played it from release not caring about it being weak (Such as myself,) tend to be more confused. And to be honest, I much prefer playing an AST over a WHM, even before buffs. I found WHM boring to play, where with AST I had a whole card system to toy with and change the flow of battle.

But I guess as the partner healer in 8/24 mans, for the love of god stop spamming cure II/III and never using regular cure. I'm not sparing Ewers for that.