I have no idea what the reason is... I can, however, say that it is not because of new ownership.
I haven't had a chance to look over the coding of the new pages yet to see what is really going on.
I would remind everyone of something Eric Shoup said at Rootstech 2012.. that new developments at Ancestry would be geared toward mobile devices first and desktops would be a secondary consideration. This may be part of that development.