Ubuntu – How to switch workspace with mouse wheel in Unity

You rely on a couple of flawed assumptions. First; it is not obvious that Mark Shuttleworth makes all these decisions. I hardly believe Ubuntu would've become such a success if he was a one-man show. It is a collective effort. Also, you assume that "this really handy function" has been thrown away. It hasn't.

Ok, now let's look at your question. It seems to be about how to launch a new instance of Firefox when there's already one running. Easy; middle-click it. Or if you use keyboard shortcuts, append Shift. For instance, if Firefox is number two on your launcher, press Super+Shift+2 to launch a new instance. You can then use Super+BAT (button above tab) to switch between Firefox instances, and you'll be moved to the correct desktop if they're on different ones. It will remember the window order, so you will also be able to use Alt+Tab to switch between the most recently used instances per application.

The cube and other Compiz effects are still available. Unity itself is a Compiz plugin, so none of those options have been removed.

There is a way to do this using the CompizConfig Settings Manager (CCSM), although it is a bit more complicated.

Warning!

You can very easily break your desktop using CCSM. Follow these instructions and any other answers recommending CCSM at your own risk. If you run into problems, see this question for instructions on how to restore Unity to working condition.

You can install CCSM by looking for it in the Ubuntu Software Center or by entering in a terminal:

sudo apt-get install compizconfig-settings-manager

Once installed, start it up and go into the options for the Opacity, Brightness and Saturation plugin. Click the checkbox to the left of it to enable the plugin first, then add a new rule under the Window specific settings section of the Opacity tab. The "Windows" textbox should contain:

Tooltip|Menu|PopupMenu|DropdownMenu

...and the "Window values" slider should be set to 90 (recommended). This value can be tweaked to your taste.

For more detailed information and screenshots, see my (source^{Expired domain}).