LOLWUT? Of course, you can click it. What are you supposed to do? Stare at it? How else are you supposed to invoke the live tile screen by mouse?
You can click in the corner. You can't actually click on the graphic (unless you're also completely in the corner).
Some items (like sleep and shutdown) have been moved elsewhere, but this right-click menu has other items that you wouldn't see in Windows 7 at all (e.g. Task Manager) or would be buried in a pop-up menu, which isn't enabled by default, or worse, buried in "All Programs". I'd rather have items that I use all the time like File Explorer, Event Viewer, Command Prompt, and Task Manager (items that I use multiple times per day) more readily available like they are in Windows 8 than something like "Devices and Printers" or "Default Programs" (rarely used) or even "Shutdown" (used maybe one time a day) like they are in Windows 7. Again, it's at worst a wash, and at best a win for Windows 8.
So the right click menu of the task bar (task bar. task manager), where its been for 17 years is "buried", but a right click menu in the corner isn't? And as for the rest, yeah some of it is handy. Some of it could easily have been pinned to the start menu (or even the start screen).
Jump lists are available in task bar items in Windows 8 just as they are in Windows 7. If you're claiming that they are available in the Start Menu or in "All Programs" groups, then I'm not seeing them in Windows 7.
Sorry, I meant the MRU lists. Point is the feature was there for one release before being cast aside to chase teh new shiny.