designers are creatives and will always believe the visual elements of a design need to be updated, refreshed, modernized etc.. then we get flavour of the month nand new trends in visual language and ui design that things must be updated to.

As soon as UI design became a creative visual thing rather than a functional thing , everything started to go crazy in UI land..

That is because they know the users. Users are very sensitive to this: if the outside wasn't changed then the internals cannot be much improved. You see this with cars, cars need a new design otherwise customer will think nothing much changed. Customer will usually buy newer over better because they think newer must have improvements, and styling signals new. Same with computers, all the disappointments when apple releases a new macbook without changing the exterior....