1. Return Of The Master
Out of all the great reasons why returning Gallifrey is an awesome idea, this one takes its place at the top of the podium. Out of all the villains the Doctor has ever had to face, The Master is definitely among the most cruel and insane foes the Doctor will ever fight, and he's far from a one-note psychopath. He's been responsible for great pain in the Doctor's life and his stories are some of the best out there. The last time we saw The Master was at The End of Time, when he fought Rassilon and returned back to Gallifrey with him. We never know what became of him or even if he needed to regenerate after his altercation with the Time Lord president, so there is a big possibility that The Master is still out there. While I would love to see John Simm return as The Master I'm pretty sure that if they bring the character back someone else would portray him. However, if they somehow could bring Simm back and indulge in some timey-wimey logic, it would be great to see different incarnations of the Master joining forces to fight The Doctor. Frankly, as long as they could keep the earlier incarnation out of the dressing-up box and stabilise his psychosis, it would be one hell of an episode. I'm sure there are more reasons to why bringing Gallifrey back is a great decision, but those five are the most important to me. Whatever they might do with this plot point remains to be seen, however I'm sure it will be one of the most important plot points in the upcoming season.