generally gameplay in the first place, photorealic amazing graphics are no use if the gameplay sucks and doesn't make fun:. it's a waste of ressources and costs if thats the matter. but i think the graphics should at least be on an adequate level to give the game an optical note which fits' to the theme, style and story and give the player even a little bit of optical comfort:.
but once a gameseries becomes famous it's somehow obligatory that gameplay and also the graphical level are on a satisfying, means not automatic towering, level:. example: fans would be disappointed for sure if the next zelda game would come along with gamecube graphics', but if the gameplay is convincing it won't be that big disaster, though nintendo won't let it be released like this, because since it is one of the most renowned gamesseries they want to implicate high quality in both, gameplay and graphics'