Overlaid 5.1.1 and 6 photos of the lockscreen music controls shows they haven't changed anything between the two. Your mockup also has more spacing issues than what we got, way too compact between the buttons and the volume bar.
The change was further back than 5.1 iirc. And yeah, that extended access view was just an attempt at not needing to cover the cover artwork any more than the default one does. I should note though, the actual spacing of the volume bar in terms of hit points, is no different from the current implementation. Visually it may look too compact, but functionally-wise it's basically the same (which was the idea, fit more without extending the bezel view)
In reality though (if they were to use the new music controls in iOS 6 on the lock screen) the double click screen would look more or less the same, just with updated buttons. I kind of doubt they'd actually ever condense the clock view to half bezel size (even if the vol. bar had more spacing).
Main point though, is that I wish they'd update the damn thing as well as keep them on-screen if something's playing. Oh and why not change the camera grabber into a music app shortcut when double clicked?
Anyway, the main thing I want in iOS is iPad style brightness bar in the switcher (posted this before but
here's a mock) along with toggles instead of a damn volume bar on the last page. I find myself chaining the brightness a LOT and it's annoying as fuck to keep opening the settings app and navigating there. That alone makes jail breaking work it, to me.