But this should not be done on a commercial product that is shipping to customers unless there's a damn good reason for it.
I kind of feel the same way you do, but modern web based software is absolutely changed all the time, with features coming and going, interface changes etc. Just about every major platform does this now, especially if its web based. Mail platforms, Word Processing / Spreadsheets, etc.
Everything has moved to "continuous improvement" methodologies. Now, whether its being improved or not is a different thing, but things are constantly changed, everywhere.