A very well written overview of animation as it pertains to UI. I think the three categories you’ve used are well representative of the different animation opportunities available to us designers. I’ve thought about this topic for a while now and read article after article, a majority of other designers always neglect that delightful bucket. There’s a sense that UI and UX is more science and data based than other fields of design and therefore anything percieved as “delightful” is fluff that has no quantifiable place. I’m happy to see that you’ve put a special emphasis on that field, realizing it may not be hierarchly as important as some interactions but it can also be the cementing factor in someones overall experience. Does twitter have to animate their heart when you like something? Does snapchat really need a dancing ghost when you pull to refresh? There are probably a couple examples you shared above which we could argue have taken the animation a bit far (except for the jiggly nav…we must have more jiggly nav…term pending of course :). It should be done on a case by case basis with the user experience in full view which, as you stated very well, includes the brand’s personality as much as the user’s need. Its also our job to deliver something that they don’t know they’ve been missing. Why keep building carriages for horses when what we really always wanted is a horseless carriage?
Long story short, job well done!