Hi Hanna,
First of all I wanted to connect this to the discussion on
Do adults exist anymore? , and specifically a nice
post by Blanca Thomas on how children don't exist anymore.
As to your question of childhood, an interesting example is menstruation (the period) which nowadays start at a much earlier age, sometimes shockingly so. Whether it has to do with our nutrition or psychology is a different question, but somewhat with both.
As for selling sex compared to cartoons, I don't know if you've seen some of the cartoons kids watch today but some are Japanese anime, where the main characters are long-legged women dressed in extra short minis and bras which can't hold their breasts. It is hard to differentiate between the kids cartoons and cartoon porn for adults. The difference might simply be whether they use white foam from hoses, as you mention, or other things.
The fact that these cartoons are not banned but are shown on morning TV I find shocking, but hey, the kids like'em (and I'm sure they will grow up to respect women tremendously).
Personally, I find the access to these shows much more troublesome than another access kids nowadays have which is to porn, in a way they never had before. A six year old can sit at home quietly watching extremely hardcore porn. Obviously this changes people, and is an awful thing, but at least it is less purposeful than the porn they are fed by the disney channel or other such channels. (In general I think hardcore causes less harm to society than softcore porn.)
One hears of cases now of orgies of ten year olds, something no one over 20 can, I think, fathom, and which is a total shock to our system.
What can we do? Not allow them to watch TV? Sue the Disney channel for corrupting our kids? Close them in a room with no electricity?
You mention the 8 year olds with iPhones, and dressing as adults. This has been going on for a very long time, but it is still shocking seeing so many 12 year olds dressed up like a 20 year old club-goer (for lack of a better word). Their faces still witness their age, but I find it to be less and less the case.