I actually worked with a MeeGo netbook for some time. In reality you launch apps with Alt-F2 and first couple of chars of app name, or just use the search box. Fast and efficient.
While I really agree with you on the convenience of the run-prompt (or dmenu-style launchers, which I use on my Arch+Xmonad machine), try to tell a regular user to start a program this way. He/she will stare at you in disbelief and then go back to clicking through menus. If you want MeeGo to sell/gain market share (and I'd group MeeGo together with Ubuntu/Mint-like Linux distros, in other words, consumer/enduser-oriented), you need a consistent and simple GUI (which doesn't mean that the capabilities for advanced users have to be dumbed down, though).
I agree that its fast and efficient to use the search box, but its something I rarely see people doing outside circles of sysadmins and developers.
The existing UI can easily be saved by just knocking out the expandable panels completely and just putting all the apps on one panel delineated by category name.