The calendar doesn't work (can't see events unless you click on a day) on mobile without turning the phone to enable landscape mode.
Also a few other things I prefer on desktop mode over mobile, such as being able to see signatures in portrait mode.
Agree with the boys above.
Quest Cape is a very good goal, having all quests means you won't be locked out of any new content.
Also achievement diaries. Hard Wildy diaries are key for pking, and all other diaries have very OP rewards.