At least the apps are being checked properly...
I'm not a Mac user - have used Debian for about ten years - but at least Apple are trying to protect the user from crapware.
Ubuntu and Gnome/KDE implement something similar - i.e. there are dozens of IM clients but the Gnome guys choose one which is the 'best' and make that the one installed when the OS is first installed. Same for FTP client, Photo manager, Music manager etc.
Also, on Ubuntu you have the 'Software Centre' to allow users to add apps. And I think the apps in the software centre are picked by Ubuntu/Canonical as ones which are good quality and they are maintained by Canonical. This is great because non-techie users can go to the 'Software Centre' and pick software and add it without worrying about the quality. Also, they are adding the ability for users to rate applications which is even better.
Of course, this being OSS I can open the lower level Synaptic package manager (or command line) and install any software I want.
(BTW - another aspect of the centralised software distribution is the seamless provision of updates. At my sister's school we installed Ubuntu PC's to run the whiteboards. The software is available from a repository set up by the whiteboard manufacturers - so by adding that repository to the repository list we now get all updates downloaded automatically as part of the software update tool. These are Promethean whiteboards running Activ Inspire software.)
Apple are being strict but that helps them keep the quality of the experience high.
I'm sure Photoshop etc will always be available even if via the app store. In fact, if there was a way to rent Creative Suite then that would be great as we'd prefer to pay a monthly amount and always have the most up-to-date version - instead of paying £1,500.00 every 4-5 years.
So you pays your money and you takes your choice - Apple which has an excellent record of high quality products and is now attempting to ensure that all software is high quality as well - or Ubuntu which has a more community based approach to helping you choose good software.
I choose Ubuntu on the desktop as it has all the tools I need - my wife chooses a Mac because she needs Creative Suite which isn't available for Ubuntu.
Either way - competition is good and the market benefits.