@Toby Cryns Theme developers have been doing the “post format” thing for a decade (only using taxonomies to control styling rather than post formats). Are theme people using the 'format' or 'post format' idea/concept, and the taxonomy mechanism, as a 'back-door style-sheet'. Is this a type of end-run around or replacement/alternative for CSS?

I must say, there is a lot I don't 'get' about Post Format. Why do we need a "Quote" format, since we have a Quote button & standardized styling for quotes, right there in the Editor, and the theme style sheet. Wanna Image? The button is already there...

Even before the UI in core issue came up, my questions had for some time been building, rather than resolving.

Mark Jaquith is right: ... [It] just isn’t compelling, or obvious, or any of the things that it should be. Of course, in the context, he is refering to the new Post Format UI per se, rather than PF more generally.

What does seem compelling obvious is that the hangup or glitch with the UI stems from/is an expression/outgrowth of problems in the Post Format mechanism that the UI is attempting to present to the user.

Mr. Jaquith goes on:... [I]t seems to be a fundamental issue with the concept.

What "concept"? The concept of providing a UI for the mechanism? Nah ... the concept of the mechanism - Post Formats - itself.