They don't understand that companies can't afford slow downs every time MS revamps Windows' appearance on a whim.
What is wrong with making it look essentially like the old version and letting people activate new features when and if they want to? Just have a "new features" button to tempt them to see if they want to make changes.
If they force unwanted changes, someone else will sell or give away a way to undo them.
Indeed. Do anything you want under the covers to improve operation and stability but stop forcing user interface changes.