Because it's double the amount of testing. The correct choice would have been not to change it and leave it as an orientation lock. Having an option in settings somewhere is just nonsense.

If you want it bad enough and don't want Apple to test for it (we're talking about Apple, not Boxee on this one right?) then I'm sure someone will release a Jailbreak-only patch for it someday.

With regards to Boxee, they too should not have changed over their UI completely and instead focused on actually fixing the problems and bugs with the previous UI. Now they have a brand new mess to deal with and have to try and hack back support for features that already existed in the old version into a framework and concept that likely was never designed to accept them in the first place.