Personally, I think Moffatt is showing respect by NOT including all those previous Doctors. They are the show's past, not its future. He's arguably shown more respect to what's come before than any previous producer, and I think he wants to preserve that legacy by leaving those great Doctors to be remembered the way they were, rather than shoehorning them into an episode for the sake of doing so - even if a servicable story could be written for it, and we know he's plenty capable of that too.
Still, he's been known to surprise us, and I think he still will here - even if there's SOME way to work past characters in. The utter disappointment of the "stings" this weekend (and man, did it sting) just makes the wait all the more unbearable, and with an impending regeneration also coming in mere months, being nice and comfortable with all sorts of fanwank like old Doctors and a current one with no hint of leaving is the last thing we need.