One of the reason for comic book becoming impenetrable to younger audience is content. As the die hard comic readers grew up their tastes changed and the books changed with them. us an effect of their primary customer getting and no new fans entering the fold. This also leads to the bigger problem in impenetrability for new younger fans.
Not only do you have comics that are tied into a continuity that goes back decades but they are filled with content that is just not appropriate from someone 6-13.Now we have stories with openly gay super heroes, graphic violence and other books being used by artists and writers to espouse their own political and social views. Not only does this make the newer books inappropriate to children but it also turns off any new adult readers who now open up a book to see Spiderman drooling over Obama or Capt American becoming a 911 truther.
If you look at the comic racks at the book or comic store you do not see any comics even being made for kids. There is one potential savior, Disney recently acquired MARVEL. Disney could with their successful shows and ownership of MARVEL could easily mend this by making comics based on their hit children shows such as Hannah Montana, Wizards of Waverly Place etc. or just make more age appropriate books with easily accessible stories based on the marvel line. So far all they have done is an Avengers toon on Disney XD and use their channels to promote marvel movies such as THOR and some new website where you can make your own comic. Now this does have the potential to bring kids into the MARVEL fold at least when it comes to other related properties. You never saw a Hannah Montana or Wizards of Waverly Place comic because even their execs are being told comics do not sell. In the end their acquisition of MARVEL was just another property they can merchandise out.