* People who criticise such things are generally do it because they don't like it, not because it is bad. Although they will say they don't like it because games are bad, or maybe another media they don't participate in. There is no evidence being presented by these people that the media they don't like is bad.
* They are being dishonest and hyperbolic. Let's take a couple of quotes from the grandparent post. "very close to 100% of the games being made seem to be about murdering other creatures", and "Part of me thinks we should drop the pretext of a "Gaming Industry" and just start calling it the "Murder Simulation Industry"."". Obviously these are nowhere near honest. 'Murder Simulation Industry', I mean come on, could you make a more negative slant against games than that.
* They often say it to belittle other people so they can elevate themselves, at least in their mind. It is like people who say they don't play 'cliche' games and say that people who play mainstream games are retards. Same sort of belittling there as well. I wouldn't trust either of these people. Why would you care about what entertainment someone enjoys? Even if it is violent, it is not like they are actually being violent by enjoying some type of media.