Double dipping rewards is a no-no in Blizzard's development team. It's also why we don't have tabards that give rep when you wear them for dungeon runs.
That's not true. Bean-counters at Activision-Blizzard wants players to stay subbed for longer periods of time. No better way to do that than make everything take just a little bit longer to do.
Even with flying around the corner in 9.1, you still have several limitations: No flying between zones as you can't fly to Oribos. No flying in the Maw or the new zone added to the Maw.