Well, if your WHMs think that Afflatus Misery is a legitimate excuse to melee full-time then they aren't so exceptional. Even in Nyzul when I can actually hurt stuff on WHM, I'm usually too busy hasting all my melees, removing enfeebles, regen-ing and generally keeping my MP up (Mystic Boon can't keep up in such situations) that I have no time for it. If they're simply trying to get hit with things so they can Esuna, you don't have to be right on the front line for that, and even if you avoid it, that's why we have Sacrifice. Maybe I don't understand your problem fully.
In my ls, since I run it, I had a night where the sole WHM was /NIN for the entire run. It actually worked amazingly. A WHM/NIN with Mystic boon and March x2, Min/Mad, and Ballad x2 is a **** beast when it comes to healing. If you did have a WHM meleeing, **** evoker's, give em melee rolls like fighter's and chaos so they can get mp back faster.
I'd say that since the introduction of Misery, WHM has made it to the front lines in my book for events like City Dynamis, Limbus that doesn't involve U/O, some salvage runs, Nyzul, Sky/Sea farms, and any event where mobs don't have extremely high levels, defense, or evasion. Hell, WHM/SCH melee is pretty **** sweet for merits these day, I'd even take it over a RDM. I mean you have more cure potency, better regens, -10% on spell costs, half cost on big spells, easy access to 5mp a tick refresh in a standard merit pt, sublimation, and mystic boon.
I know this isn't all on topic or anything, but to say WHM's who melee aren't so exceptional, is just sheer stupidity. Melee WHM can be put to amazing use in the right situations, if you have a WHM good enough to pull it off.