I don't think Im alone when I say this has been a sad path that Apple Apps have been slowly following. After making a big deal when the iPhone was released about how all apps should be coded to support both portrait and landscape mode this would be one of the few changes that I can't understand a reason for.
I use my iPhone and iPad only in Landscape mode. I have no desire or want to use it in portrait mode. I do not want to use apps that only support portrait. The App Store app was a huge disappointment, and I am forced to use it is an essential part of the infrastructure. When Mail on the iPhone changed so it no longer supported frames in displaying a mail and mailbox, I stopped using it. And now the Weather app supplying you with less options, I have stopped using it.
Please, if you feel the same way let Apple know not limit our options and the way we want to use our devices, but expand them and give us more options. This current trend of portrait only doesn't match with the Apple I've known since the beginning.