Lucky if a SP is 6-8 hours today, in the good old days 20-30 hours.
As for peeps crying about MP, many great classic games up till mid 2000's were SP only and not everyone likes MP.
I remember those good old days, where you buy a game for the single player

I still mainly buy games for single player and would rather they spend all their resources making a good single player game. Then having a MP that only lasts a few months anyway, as people tend to move on to the next big game.