I just don't find dragging the pointer down the left edge of the screen to require that much effort. Also, any app that would run on Windows 7 or earlier would have to be run in Windows 8's desktop where you would still be able to cascade their windows.
While the "full screen" apps are usually displayed one at a time you can drag one of those thumbnails into the display to experience two apps "tiled" horizontally on the screen.
While Microsoft was probably wanting to make PC Windows function in a manner closer to the way tablets work there are some other advantages. I've noticed a tendency towards desktop applications (including Microsoft Office) using a growing percentage of screen real estate with side bars and tool bars (sometimes called "ribbons"). That leaves significantly less room for the actual document, which may be a web page, spreadsheet, data table, source code listing or photograph. In the Windows 8 apps the tool bars and menus are hidden along the edge of the screen in a manner similar to the task bar in the earlier versions of Windows when the hidden option was activated.
I don't see where the quick launch menu is significantly different from items pinned to the start menu in earlier versions of Windows or the start screen in Windows 8. The start screen in Windows 8 is a quick click in the lower left corner of the screen away, very
close to where earlier Windows versions normally placed the quick launch menu. Start screen tiles can be rearranged by the user so that frequently used apps (full screen or for the classic desktop) are conveniently on the display without horizontal scrolling.