Regarding the recent announcement about the upcoming revision of Yahoo! Mail user interface, I'd like to express my thoughts regarding the change as a mean of feedback.
I know I'm not alone, as this is commonly the general sentiment online, in saying that changes in the UI of a product that is commonly used and not considered faulty are largely unwanted by the users.
"If it ain't broke, don't fix it" is a common saying used in these contexts.
Oftentimes, the perception from the users is that these unwanted and uncalled for changes are more of a byproduct of people getting paid for working on R&D that have to somehow justify getting paid by their company, rather than something users want.
Rather than having unsatisfied customers begrudgingly having to adapt to changes they didn't want in the first place, it would be better to always leave these changes to the UI OPTIONAL.
Users don't mind having more choice, but they DEFINTELY don't like someone else making choices for them.

People at large really, REALLY dislike these UI changes. Remember that people at large are creatures of habit. And functionality and familiarity are more appreciated than change for the sake of change.