Anything is good for airsoft if it gets more people playing.
You reference the big military based first-person shooters, there's just as many non-military ones out there. From milsim perspective, I think it's down to you guys running/playing it as to whether it becomes a good or bad thing.
If you're open minded enough to accept fresh-blood and guide them (at risk of getting occasional total idiot, but whens that not a risk?) then it's all good and the ranks will swell, more good times for all.
If you're too snobbish and dismissive to not want anyone who isn't acting/dressing in a 'professional' soldering manner already participating, as they taint that precious sense of immersion, then you'll prob successfully put them off by being a dick, or encourage them to treat you with an equal lack of respect. More bad times for all.
If you think the computer games mentioned are unrealistic or incorrect, and this is damaging the sense of milsim immersion due to it being incorrect, then again it's the same decision; guide/help/persuade people to accept your 'truth' or dismiss/be a dick. If the influx of people influenced by these games was so great that it eventually lead to a situation where the 'military realism' perpetuated by these computer games ended up eclipsing or replacing the the current ethos in milsim and airsoft, then tough luck thats just cultural progression, it was more popular so it won. Sure wouldn't be hard to start an 'old-skool' milsim league if/when necessary.
Personally I don't care what makes someone want to play airsoft, as long as they don't think it's the only valid reason or ethos. I also don't care what kind of ethos people play with. If (as mentioned by AK47 above) a bunch of kids turn up expecting to re-live CoD, then who am I to stop them (other than by shooting them ofc hehe). It's snobbish to think their ethos is any more or less valid than your own. At the end of the day we're shooting each other with toy guns and a kid shouting he 'no scoped you' is no more ridiculous than someone using 'real' military terminology. If your sense of fantasy is so precious it can't handle conflicting things going on around you then form a club of like-minded people or see a shrink. As long as people stick to the rules it's all good however they want to go about playing. If they don't they'll be quickly kicked/banned anyways.