The trouble with your question is that you've left out any mention of the .dmg that the user actually downloaded. Don't get me wrong, I like disk images as muc

The trouble with your question is that you've left out any mention of the .dmg that the user actually downloaded. Don't get me wrong, I like disk images as much as the next nerd, but it has been my observation that there are way too many ways for the process of getting from .dmg to in-dock-ready-to-rock to go awry. People can and do figure it out, but the process is still far from optimal. "Internet Enabled" disk images were an attempt to deal with this, but not every application ships as one, not every browser supports them, and plenty of people have the auto-open option turned off in Safari either because they think it's obnoxious or insecure. (And even if it works perfectly--even if the .dmg turns directly into an .app--the .app ends up in ~/Downloads/. Where for some it will forever remain.) So you're left, at least some of the time, with this file icon with a weird silvery box thing on it. If you're lucky ("you" being both CEO of n00b, Inc. and Mayor of n00btown) the download page of the application (or if you figured out how to mount the .dmg, within the .dmg itself) you just downloaded has instructions on where to go from here. (Instructions which you, Hacker News reader, have seen a million times without ever really noticing that they are a symptom of a problem.) But let's suppose there are no instructions. But you can figure this out. You're Mayor of N00btown, after all. So you double-click the .dmg and here's a new window, and yay, there's the app icon. ::click click::. Yay! Bouncing icon in the Dock! It works! And it will probably continue to work just fine...until you shut down or restart (which could be six months from now--given how busy and productive you all are at n00b, Inc. you can't afford to waste time every week on "Software Updates") at which point your disk images unmount and suddenly some of your programs just don't work anymore! So you download them again... The thing is, none of this (the many ways users can fail with installation) is so disastrous or commonplace that it constitutes an Obvious Problem that Must Be Addressed. Even in the above scenario (which is only a little contrived) the applications still actually work. The user is not confused, but there is still a pathology at play. The user does not go complain to their nerd until things actually fail, and the nerd typically puts a band-aid on it and asks the user to stop doing the wrong thing, while the root problem persists. My point being that even if the ".app inside a .dmg" approach to installation isn't "extremely confusing" (and I would agree, even after the above, that it is not) it still has an unnecessary capacity for undesirable side effects (including confusion) that you don't see with an app store or repository approach.