I hear where you're coming from Rob.
We kind of think. Oh just do Sgt Peppers, I Feel Fine, Back in the USSR and so on. Trouble is, I expect there's one hell of a lot of arrangement that goes into the set list they perform live.
Not like Paul has the other 3 Beatles or Wings behind him and they can simply rattle his whole back catalogue off with ease.
On the other hand, they must have known for a hell of along time they were doing Glastonbury and could have prepared the ultimate "sing-a-long" set.
The upshot is, McCartney is pretty much musical royalty, has absolutely nothing to prove and can do what the fuck he likes.
As you say though, no big deal.