When I switched to the Mac I was surprised how easy it was to install and uninstall applications in OS X compared to the horrible installer workflow and the Add/Remove Programs Control Panel of Windows.
For those that are unaware, prior to Lion installing an application on the Mac went something like this; download a .DMG file which would mount to your Mac much like putting a CD in the disk drive and dragging the application icon into your Applications folder. That's it. Drag, drop, installed. To uninstall an application you just delete the application from your Applications folder. Done.
The caveats to this process were the need to unmount the DMG after you've installed the application and then trashing the leftover DMG files in people's Downloads folder.
However, with Lion came the promise of simplifying this process even more. Why? Because, although the above process seems simple it wasn't nearly as simple as Apple had managed to make installing and uninstalling applications from iOS. On iOS you open the App Store, click Install, the application's icon shows up on your device's Home Screen. If you'd like to uninstall the application you tap and hold the icon, an "x" shows up, click it and confirm that you want to uninstall the app. Very simple.
Lion wanted to bring this very same workflow to the Mac. The workflow goes very much the same; Install applications directly from the Mac App Store, the application's icon shows up on Launchpad, click and hold to uninstall the app from your Mac.
However, on Lion not all applications are created equal. Some applications were installed prior to, or without the use of, the Mac App Store. Perhaps you downloaded the application from the web or you simply have it installed from long before Lion. Either way, these applications still show up on Launchpad - they just can't be uninstalled from Launchpad.
Which is why I think uninstalling applications on Lion is arguably more difficult for some people because the workflow for one application is different than the workflow for another application. If Apple could have allowed for applications that were not installed via the Mac App Store to be uninstalled using the same workflow they would have. There must be some very good reasons why they can not - however, I thought that they should have at least showed a dialog to instruct the user on how they can uninstall the application anyway.
For instance, if I've got Launchpad open I can drag the application's icon to Trash on the Dock. Shouldn't this uninstall it? If I was in my Applications folder and did the very same thing it would. So why not from Launchpad directly to Trash? Why even allow me to drag it over the Trash? Why not show a message when I do this: "Sorry, but you'll have to open Finder, navigate to your Applications folder, and remove the application from there manually."
I'm not sure why Apple didn't find some way to either make this easier or to inform the user how to accomplish this simple task. But a few years from now, when 90% of all installed Mac applications have been installed directly from the Mac App Store, Apple will no longer need or care to worry about this issue. And perhaps that alone is reason enough for them not to care about it now.