It funny how things change from gen to gen. What was not so acceptable then, is acceptable now.
Out of boredom, I check metacritic score for warhawk and glance at a few reviews and this is what i stumble on.
From a website review
Worth Playing, 90, Perhaps the highest praise I can give the title is that despite Sony's concerns with overpricing a multiplayer-only game, Warhawk, lacking all single-player capabilities, is worth every bit of the full price for games of this console generation.
So, back then an only multiplayer game worth 40 dollars was, how to say, frowned upon. But today, a 60 dollar only multiplayer game+xbox gold is within normality or just 60 dollars for pc or however much it costs for pc. Speaking about titanfall. And not only about that game, but about games to come.
Though games still shouldnt cost full price if they contain only single player or only multiplayer. Though, I do not make prices, so, What to do.