Seems like Sony and MS decided to rush to market and it resulted in two consoels that lacked many features of the previous versions.
Again, its a result of starting over. They couldnt just port features for whatever reason. The reason they took this hit was mostly due to the fact that the 360 OS was simply too limited to carry over to the next gen and offer MS the flexibility they wanted. Moving to a windows 8 core opens up a lot of options, but it means they have to suffer this period of severe lack in features.
Sony made a similar choice for the ps4, sacrificing many features of the ps3 in order to build a more robust OS for the future.
I'm not talking about literally copying and pasting code, but they didn't think to include parties and have them behave like they did before? They've stripped back the OS to barebones almost and only worked on the new stuff exclusive to X1. And yeah, this is an issue for both, I'm not picking on MS/X1 here. Removing CD/MP3 etc was a foolish move.