As the market grew, consoles became more popular, because people were buying games just to play games, instead of a thing they could do on the computer they already owned. It became increasingly necessary to be competitive, and increasingly expensive to make games. Now they cost millions of dollars to make. You have to market them to as wide a demographic as possible, because a flop is too much of a financial risk. Thus, they are often watered down with mass appeal. You have the strange result of these huge, blockbuster games that are also stagnant and shallow, and people love them or hate them. Many PC gamers are frustrated because nobody makes the games they like anymore. When it seems like they might, they don't. When the PCers try to push toward someone making a game they want, others shoot them down and want it to be more like everything else, because they are lucky and in the group that likes the available games. They see no problem with this because they figure it makes the games better, and don't understand that what they're basically saying is "you should be happy with nothing while I get everything", and that it is infuriating.
Of course, the cruel whims of capitalism are not the fault of console gamers. They are, however, the beneficiaries of it, and the losers will inevitably become bitter toward the winners...especially when the winners unknowingly tend to rub it in their face. The anger is justified but the targets are not, and then the targets fight back with claims of elitism and nostalgia goggles, which ironically is taking their justified frustration at being attacked and turning it into an unjustified counterattack right back, effectively telling the other side that their favorite games and fond memories of being the favored demographics are are bad and they just don't know what they're talking about.
Or, to put it short and simple, console/PC wars have nothing to do with PC users modding the game. Like all arguments, it is because people are stupid and/or jerks.