Landscape Lock Screen Concept By Jake Marsh
The iOS lock screen may appear simple and almost featureless at first glance, but it actually serves quite a few different functions, and adding landscape support for all of them is certainly a non-trivial task. Again, it strikes me this is likely the reason for not supporting this yet, given the almost certainly enormous complexity of this part of iOS’s codebase.
There is a lot of effort involved, yes, but it’s disappointing that Apple didn’t make the effort with the iPhone 6 Plus. It’s a bit hypocritical for Apple to expect third-party developers to go the extra mile and optimise app layouts, when it can’t dedicate the time to do it fully as the platform vendor.