This is my problem with Ubuntu and Unity, and why I much prefer Linux Mint as a "Windows replacement" OS. They say they made that side bar to "work well with touchscreen devices, too", but as we can see Unity on a touchscreen devices offers a pretty poor experience, and the sidebar is just about the only thing that is meant for touchscreens in Ubuntu. The global menu and everything else is clearly meant for a PC and a mouse.

So why annoy the PC users with the sidebar, when it's not even that good of a UI for tablets? They're much better off designing a tablet-first UI for tablets, if they want to get into that, and stick with designing a well optimized PC UI for PC's.

I've never been a believer of one UI for all form factors and sizes, because you usually end up with the UI being optimized just for one form factor and size, and mediocre or downright terrible for others. You need to optimize the UI for its own form factor and size. It's the only way to make it work well.