There's more to a video game than being pleasant. The Genesis Sonic games had distinct imagery, complex level design and likable spirit, serving to do more than placate. The Dreamcast Sonic Adventure games fail to consistently engage most adults, and some of the engagement that is there is frustration, but at least they surprised you. With Sonic Generations, Sonic Team got so neutered by decades of fan complaints against their risk taking mentality that they retreated into their shell, making a perfectly serviceable game but one that touches nobody, and changes nothing. They probably haven't made a game as good since, somehow.