I agree with the majority of his reasons. I personally do also not see a single valid reason for having post formats - altough I was wondering about this feature ever since it has been included into the Core. But to be honest - the whole content logic of WordPress needs a lift anyway (from my point of view). It should be centralized as "Content" instead of having posts, pages and various post types, and by creating new content the UI will lead through various options, adding taxonomy select boxes or custom fields (based on the type of content which can be anything like post, page or cpt) - that would make things easier to understand and to work with. And it would unclutter the overladed admin ui (admin menu items for each post type,...)

So, yes - move post formats into a plugin and yes, rethink the whole concept of content creation (altough this doesn't gets discussed in this ticket) :)