A, dmg, I think that you take Guy's words too literary.
I think what Guy means is that as a participant in the creation, the old material bring little joy to the creators, simply because they have come full circle.
The creative phase is an ongoing effort. And they enjoy the new, yet to be created material, because it is challenging and give them reason to carry on.
As a listener, it is a completely different thing. Recorded music is timeless and new to people that listen to it for the first time even if it was recorded 130 years ago on wax.
And I think that MK has said a similar thing and he tries to please his audience by playing older songs, because he understands the difference.