@Michael, @Albert: do you actually have a way to collect statistics on how many people use post formats, or are you generalizing from your personal experience? Millions of people do use WordPress primarily for blogging, or consider a blog an important part of their WP site, and so might well find a better implementation of post formats helpful.

Most of my clients are using WP more as a CMS than a blog and are not big users of post formats, but one of them just decided to use Asides to announce her workshops, because they show up with a blue background. (She's using a child theme of Twenty Twelve.) Semantically all wrong, stylistically appealing to her. Technologically she falls into the Hopeless N00b category, but discovered this herself. I have another prospective client who just requested post format styling without knowing that's what she was asking for. (She wants her photo gallery posts to look different from her text posts.)

I am not a hopeless n00b, but I found that the new post formats UI made the various post formats easier to use. It was never obvious how the link post format was supposed to work in 3.3-3.5, and having the title disappear in some post formats was a surprise, since it showed up in the editor. The new UI in 3.6 made things more consistent between the editor and the published post. My students were looking forward to it; ditto the members of the East Bay WordPress group, who saw the demo.

The existing state of post formats needed improving. I think it was already a considerable improvement, and it appeared to be working, though my tests were limited to the Twenty Thirteen theme. Perhaps the UI overhaul is not finished, so needs to wait, but that doesn't mean it's not appropriate for core.

As for the redesigns of the admin interface, they are not a whim, but an attempt to make it more accessible and to fit more things into a cramped area. Also to make the WordPress admin responsive, because the iOS app is of very limited utility. Whether these redesigns are SUCCESSFUL is perhaps another question, but they are done with a purpose.