It really just depends on the game. You can either look at a game like Titanfall, or the upcomming Evolve and say "hey, that game only has MP, how dare they charge 60$ for a game with less content!" Or even MGS Ground Zero wich only has about 3 hours of content for 30$!
But then you could also look at games like Skyrim, GTAV, Destiny, Watchdogs, ect where you are actually probabally getting more content than what ypu payed for with the 60$ price tag (100+ hours each).
So I think it goes both ways, and as a gamer you have to be carefull with what games you chose to get. I personally got Titanfall, and while I was dissapointed with no SP, and only 5MP modes curently, I still don't regret my purchase as I'v had hours and hours of fun with it.
