But 99% of the usability issues people have is due to the loss of the start menu.
I seem to recall the decision to remove the start button being based on data from the Customer Experience Improvement Program... such as most users NOT clicking the start button and most users relying instead on pinned frequent apps.
Non-RT versions of Windows 8 still run desktop apps just fine. I vividly remember the new start menu landing in the internal builds of Windows I was running a couple of years back. Sure there was a brief learning curve (same tends to happen anytime you do a major rev of... anything).
Windows 7 has long been banned from my home, and now everything is running Windows 8 and all are happy... even in cases where the device is not touch enabled.