As of today i think it's just the statues quo. People don't tend to question it as it's always been this way. It's just business as usual.
Except it wasn't always this way.
PS2, DC (for a while), GCN, Wii, Wii U, PS3, Mac, PC,... all free.
Seems that most people who accept pay to play online grew up with consoles only and mostly grew up with the 00 generation of consoles and mostly XBox users.
Maybe back in the early and mid-90s, when other companies had to create portals and patches to make certain games work online (Kali, MPlayer, Dwango, XBand, etc), it made sense for them to cost money to use them, because these companies added their own stuff to these games that wouldn't be available without them. However, some of htem were ONE TIME fees and you were good for unlimited use thereafter. Many others were free.
When Blizzard created battle.net other companies started creating their own software and servers to make the games work online. This was included with the cost of the game, and it still is... except there's now a middleman at work with consoles.
MS did a lot of underhanded shit, like trying not to pay royalties to use music from less famous bands in their games and it lines up with their barring access to online play unless you paid a fee. And that's what each of these middlemen are doing, they're barring access to Activision, EA, etc unless you pay up for their service. They try to hide the fact that they're doing this by giving you incentives, but it's still nothing but a blocking service.
There's a reason almost no one pays for shit on PC/Mac/cellulars, because they still have a choice. With consoles, you're not given one. It's their way or nothing (not counting MMORPs and other server based of course, but even these can have free servers)
