The noun mediocrity means if something is of average quality but you think it should be better.  

Synonyms are normality, averageness or commonness.

The word origins from the English via the Middle French from the Latin word mediocris, which means of medium size, moderate or middling. The word was at first neutral but over time it changed to a more disparagement meaning (speaking about someone in a negative or belittling way). In the 1690s it developed to the meaning of “a person of mediocre abilities or attainments”.

They all accepted that mediocrity was good enough for them.

We were disappointed by the mediocrity of the dinner in a michelin star restaurant.

Some became famous after the show, where as others have fallen into mediocrity.