i love the idea of a new TARDIS, frankly a TARDIS is as personal to a regenerated doctor as can be, it not only reflects the emotions of the doctor but it also reflects the entire series as well, 9 & 10 have both shared the same TARDIS, and even the earlier version commented that it was 'spartan' (at least i think ) the 9th was still recovering from his time war experiance and 10 was being broody over blondie. () since both seem to have been put to rest it should only feel natural that this new doctor would want a change of scenery. the 'desktop theme' would possibly hold too many memories for him.
and i fully support Steven Moffat. his episodes are amazing and it should only be right that he'd want to strike out on his own, create his own unique doctor, his unique style and of course, unique episodes. believe me, if your a fan of Blink, Silence in the Library or The Doctor Dances you will most definately like the series to come.