Not everyone prizes efficiency above all things, even military pursuits. If that were the case, nobody would use marksdwarves ever aside from very specific situations, because it's highly wasteful in materials and take forever to train up.
Another thing would be that I'm sure many would consider it more trouble than it's worth to retrain a macedwarf to use a hammer or sword. Or at least I do. I can't really speak for others.
Additionally, I will agree in 34.11 and back, using a mace was basically pointless. Like... Truly, utterly pointless. They worked great in support roles, snapping limbs and such along with hammers, but tended to fall flat of edged weaponry. As an example, I had a macedwarf beat a forgotten beast practically into submission, but without pulping, she couldn't kill it. Too damn big.
However, with torsion and pulping damage, they're actually viable weapons in thier own right now, should one want to field them en masse or a dwarf happens to come with some skills in it.
Save most likely against larger foes. I'd definitely recommend anyone send in the spear or swordsdwarves for those.
EDIT: No, pulping not overkilling. Edged weapons can't always kill with a few hits or severed limbs. A weak dwarf with a copper or even bronze sword may very well need to "pulp" the son of bitch he's wailing on. However, in that same vein, an exceptionally strong wrestler may well crush a human's chest with a single punch, as was the case in a recent fort of mine. Bastard never let anyone else actually get a kill shot in.
But now, the problem we hit is what we're suddenly comparing.
No matter what, no blunt weapon will ever outperform an edged one in terms of being able to kill efficiently. Blunt weapons can't cause extreme blood loss, severe limbs, or cut a man in half. They have to hit with enough force to smash that man's limbs into jelly and then cave in his ribcage or skull.
However, in recent versions, they can no do much of the things they needed to be properly deadly and truly debilitating. And that was the main point. Maces aren't "good" compared to edged weapons; no blunt force weapon ever will be. But they can be called "good" compared to how they used to be, which was at best vendor trash or trap filler.