That's is actually not my concern. As a consumer, I will not care I can only get Metro app on the marketplace, I will just say whoever app devs didn't switch are lazy.
But, as a desktop loving consumer, I work in desktop. So, if Adobe released a Metro-fied PhotoShop, I still want to operate that application in desktop. If not, I really don't know why I would want to buy the Metro version when desktop version is clearly more suitable for my need.