I don't know about this, F50. This could be true, but it's possible it may have been the other way around and he slipped into his comfort zone with the album. Either way, it's not necessarily a bad thing, IMO.
Can you remember when Joe stated that the Eagles have finished material? I vaguely recall him mentioning that they had been working on some songs, but I could be mistaken. Of course, working on stuff can be very different for these guys than finished stuff.
Sorry, but what's easy is for armchair quarterbacks to sit back and proclaim how easy it is. For this band of perfectionist, it is apparently a very grueling process. As I said before, I don't think it's a matter of can they do it, it's more about if they want to do it.