For me the most insulting part is the inversion of priorities in these designs. The top priority of a UI designer SHOULD be to make the user as productive as possible, yet making me wait for something that is by definition not necessary (like an animation) is nonsensical. A related backward trend is this idea of pushing something in front of my face as a modal panel, with complete disregard for the fact that I was working on something and am now (a) distracted, (b) completely unable to continue doing what I chose to do, and (c) will have problems even after the modal goes away, taking extra time to figure out how to refocus on whatever I was originally trying to do before being interrupted.