The point being that, if HNMs aren't killed for the challenge, and HNMs aren't killed for drops, then their being killed to waste time. And if wasting time is all you care about, then what does Square ultimately have to gain from devoting resources to make you happy? You're still going to go back to the same old mobs, QQ about their drops and complain that Square is full of shit.
Its illogical to say that Square has flawed game design while being upset that they didn't recreate that same flawed game design to take up your time. I can understand being pissed off if your expectations were to get new HNMs with good drops, but everyone should know that its incredibly unlikely to actually have that happen.
What does Square have to gain by creating more HNMs that drop nothing, when the end result is that you'll still be complaining.