Same thing happened with Google maps a couple of years ago. They changed the UI to one a lot less functional, gave users an option to use the old UI for a while, then took it away. Now we're stuck with gmaps that are much worse than they used to be. Product managers at Google (and everywhere else) don't get promoted for leaving good products alone.
Sad but true. Redesign is also a great way for managers to increase their budgets.
"If it ain't broke, redesign it."