There are more great players who have NOT been on the cover of GP than HAVE...
No disrespect to GP, it's just that there are so many excellent players, and so little time... oh, and a lot of them play in styles that are not massively popular.
As pointed out before, all one needs do is paste a photo (cartoon, maybe?) of fave artist, or even yourself on the mug of whoever's featured.
Maybe that could even be used as a DIY cover sometime, as a commentary on the never-ending controversy about who should be featured.
You know: generic image of guitarist surrounded by a gaggle of faces with dotted lines & instructions.
Feel free to use that idea!