[timwiseman]

Perhaps part of it is that it is a reminder of lack of control of cloud based software? With most traditional software, if I dislike the new version I can continue using the old. With cloud based software, including just about all web based programs, when there is a new version my choices are to use the new version or switch to something else entirely (and if the product has any form of effective lock in, the second may not really be an option).

People like the feeling of being in control, and a change they did not expect and cannot undo undermines that feeling.