Since when is asking for actual reasons ("I don't like it because I don't like it" is not a valid opinion, in my eyes) a "high horse".
> just downloading a .dmg is way less overhead, by definition.
That's a very subjective opinion. Each time I do a fresh install of OSX, the MAS apps are always the quickest and easiest to re-install.
The only valid (but not really defensible) argument I've seen yet, is the one about not paying for commercial apps. Every other claim that the manual method is easier, just doesn't hold up.