Never did understand the 'they're too young for games argument' If kids enjoy them and the content is age appropriate, then what's the problem? Time limits have to be applied (no need to do this with a 2-3 year old due to short attention span), but that's like all good things i.e. let them have a few sweets rather than a bumper pack, an hour of TV but not a whole afternoon etc.
While I almost fully agree - time is a problem here. There are so many other things kids can and should do, most of them including either beeing outside and or training their (fine) motor skills / muscles or giving them inspiration (a game or movie limits that a lot), that gaming is on a very low priority on an "what I want my kid to do" list.
To me games are a far better form of childrens entertainment than TV / watching films and yet few parents have a problem with a 2-3 year old watching TV in moderation.
Generally speaking it is the same for me, I even like it more when my children are playing video games , and with that actually participating in whats "happening" instead of just staring at a screen. Unfortunatly me wifes sees things differently - which is something I don't fully understand with her spending a big portion of her childhood in front of an Amiga, maybe because she isn't into gaming anymore.
If the content is not age appropriate, then what's the problem? Age appropriate rules sounds like what you're saying you've never understood. I agree, but I've never understood that rule either. I had less nightmares as a younger child than I do now as an adult, and I was able to change my mind faster and with less difficulty as a younger child than now. Alcohol apparently screws with brain growth at young ages, but I've never heard of nudity and violence harming children.
The first problem is see is, when you try to create a set of rules for a large group of people, is that you have to generalize things in order to able to enforce these rules (otherwise you will be completly occupied by discussing things with people that are/feel restricted by those rules) As this rules have to orient themselfs on the most easily affected people of that group ,this means that a big (if not biggest) part of this group is hindered by that rules (even if it weren't really necessary).The second problem I see in that matter, is the (very, very old) discussion on how media we consume influences and/or effects our mind. Of course there are such nonsense theories that want to imply a direct and comfortable direct connection, like everyone who plays ego shooters will have no problem shooting people later on.
But our "Neandertal" brain evolves by experience, meaning everything we experience will be catalogued, classified and put into relation to our past experiences. With repeating experiences getting a a higher priority in this relational model. Take depicition of sexuality for example: Going back some 100 years (when people were still waering swim suits that covered the whole body) showing a still frame of what you can see on TV shows nowadays would have coused a public outrage.
Wether this is a good or a bad things, is not our concern here, but that there was a consesus in the public opinion what is appropriate or not, which has changed a lot over those years. And of course even back then there were shameless people that showed their calfs, but the majority of people formed this opinion, simply by experience > parents saying what parts of your body need to be covered or by books (or radio shows) enforcing that view or playing with that taboo, encounters with other people, etc.
This works the same way with any other experience a human brain makes. Of course there is no direct connection but beeing repeatedly exposed to certain pictures/sounds or more generally motives (like violence) will leave a mark (connections in our brain), and this mark deepens the more of the same experience you make.
Some might say now, that this is nice and such, but that its different in this case, as we (and this means usually kids too) can make the distinction between reality and fiction. Well, yes and no: While people usually are aware of the the differences on a concious level, subconciously it gets more complicated. Yet again the machanisms that the human brain has developed in the stone age has problems keeping up with technology. As several studies made pretty clear, people can get very attached to fictional characters - and I don't mean 14 or 50 year old girls throwing underwear on a stage, but people unwillingly creating relationpatterns to characters depicted on TV that are quite similar to those that exist for friends in real live.
Third problem: not all (wo)men are created equal. You provided anecdotical data, that you weren't really affected by watching some things (which I guess weren't age appropriate) as a kid. I can counter that with me watching ("thanks" to father not caring about age restriction) a lot of age inapproriate video material as a kid, resulting in me not wanting to take a swim in the sea for many years after watching Jaws (and even an uneasy feeling when swimming to a ladder of a swimming pool, feeling an urge to rush to the ladder), and beeing quite quick in switching the lights on in dark areas because I feared that a creation of some swiss guy called Giger would grab me out of the darkness (I think I was 7 when I first saw Aliens).
This does not mean that you are "harder" then me or some kind of special case, just that as different the skill sets are, everone posses, so are the abilities to cope with more extreme experiences. And this gets even worse if mental instabilities come into play.
With that in mind, circling back to the first problem I see: We have a part of a group which definately has no problems seeing such things (represented by you) and another one that has a harder time coping with "harder" material (represented by me) - which one should represent the case were we scale things on ? I vote for the latter group, not only because I'm in this group, but simply because of the question "What harm is done ?" > What harm is done if some kid sees something like Aliens with 12 instead 10, or plays Doom with 14 instead if 8 ? Is there any reason to belive that he will be harmed by not seeing it or looses something he can't make up for later on in his live?
Just think learning how to handle a C64 is better than learning how to use an iPad
