I want my UI’s to be usable. I want it to be immediately obvious what I need to do. I want them to become invisible in the same way good tools do. I don’t want my hammer to be quirky, I want it to be an extension of my hand.

EDIT - Yeah. I have a certain fondness for Kai’s. But I had time to get used to them. It’s one UI in a thousand where I have time to get bedded in with it’s quirks. For all the rest - be boring.

The flat UI's you're complaining about are an example of the form over function philosophy.

The opposite could be argued as well: it's design supposed to focus on function alone (after all that was their pitch: put the content front and center, remove aesthetic touches from the "skeuomorphic" UIs, etc.) but with no redeeming aesthetic qualities (which are also important for actual human users).

So, it's not exactly form over function (besides thought into form is necessary for function - you can have a real world lever that is e.g. thin and crooked and it will still function as a lever, but a good lever also has good form -- e.g. be designed to have a good grip).

It's "design ideology and novelty for some manager's sake" over form and function.