They were a bit rubbish because nobody really cares about wallpapers, so they replaced them with Mastery which was less rubbish, with actual in-game features to unlock, but far more broken. Last year we were told that Mastery would be fixed "after Christmas", but they didn't specify which Christmas.
To be honest the poster idea was rubbish and mastery is rubbish, i just love driving trains so not fussed about scenery