He's overrated.

By jove, this young lad is daft.

He is the cause of everything! He founded Freddy Fazbear's, He killed the kids who haunted the animatronics and he set in motion the events that lead to the mimic going rogue. Saying Afton is overrated is like saying Dio Brando is overrated. He is THE big bad of the franchise. Even after his final defeat at the end of Pizzeria Simulator, The consequences of his actions still linger. So great was his evil that his remnant gave birth to Glitchtrap, the entity that turned Vanessa into Vanny and current'y controls the mimic. So no. William Afton is not overrated. He is the driving force of FNAF's story as a whole.

sorry but for your information his deeds are the backbone of the lore, and therefore deserves respect especially after tearing himself back out of hell, destroying animatronics by himself in his human form and proceeding to control many animatronics at once. there is no one character who has managed to pull off the crap he has, being able to make more refined versions of animatronics then henry could and coming back to life many times over. and thus this is my over the top explanation to say "no, he is not overrated".

Not to mention being reincarnated as Glitchtrap