I see what you are talking about first hand locally with younger builders fleeing, and its very sad to be honest, the attitude alone from a lot of the age demo graphic is enough to send kids or young adults running, I have seen it ruin a so called "friendship" here over different thoughts and ideas and interest with stuff pertaining to the hobby, and that is sad, as we are just building models. But the other thing that I see that might be a big part of keeping kids/younger builders away is the way some guys in the hobby act like its "their hobby",and they dont want no young wipper snappers coming along and wanting to be different or what have you.
Its sort of like these guys act like its an elite club and you better like to build what they do, and have the same interest as they and have the same opinions about everything else in life , the entire mindset of the hobby is bad, and that is not going to be very inviting to younger builders.
And , lets look at the other aspect, you cant make kids want to build models, they have to "want to", so it doesnt matter how many kits Revell does that are aimed at the younger builders, if there is not interest, its not going to happen.
I will say that my local clubs here do a wonderful job at trying to get the kids interested with "Revell's Make And Take" program, there are I believe three times in the Phoenix Metro area that we do them, twice at the GoodGuys show, and one during Desert Scale Classic , and I must say that all the guys that volunteer do a wonderful job with helping the kids.