I dunno, while the presentation is radically different for Marc, the actual clothes and where they're coming from in this collection are honestly closer to what he became known for than either F/W 06 or S/S 07.
He made himself famous by reworking vintage pieces, sometimes abstractly but most of the time pretty literally. F/W 03 for instance was extremely literal in it's appropriation of 60s mod design, and imo was no more nonchalant or effortless than F/W 09. Six years down the road I still can't imagine how those pieces would be worn without looking costumey. S/S 03 was just as literal in it's take on late 50s/early 60s fashion, and those clothes were some of the most prissy, pulled-together clothes that Marc has ever done.
I don't think you can really hold this collection up against F/W 06 and S/S 07 because out of the examples you've provided, they're the two that stick out like sore thumbs. They were completely experimental for Marc and along with S/S 09 were the only collections where he managed to successfully blur his references enough that the end result seemed new. The rest of the collections you pointed out just seem so nonchalant because Marc intended for them to. I mean, give the models from F/W 06 dirty, smudgey eye makeup and ratted out hobo hair and it wouldn't look so effortless anymore, it would look like a New York version of Galliano's "homeless" collection. So even though all of those collections seem so effortless, they really weren't any more than this collection is.
I really don't think his aesthetic has changed. The way he packages it is what did.