That's nobodys fault.
Because asking an artist to do a better piece of art than the previous one everytime is almost impossible, if not impossible alltogether.
It would be like demanding Leonardo Da Vinci to do a better piece than the "Mona Lisa" right after he drawn it.
It's impossible to always do a better piece of art than the previous one.
Therefore a system should be in place to give incentive every new expansion to look cool.