What is exactly is "Age-Appropriate" ?

After ten plus years of living, breathing and reading autism, I have many areas of disagreement with accepted teachings and practices.  Most due to the current one-size-fits all education practices.  But one of my pet peeves is the "age-appropriate" goal.  In this day and age where couples honeymoon at Disney, both Grandparents and toddlers wear Ramones Tshirts, Starbucks serves cakepops, and most of us use text abbrevations, that term is up for debate.  

Why is my son's love of Bob the Builder wrong when masses are dressing up for ComCon? He is twelve, loves Chuck Berry, Bob Dylan, Sponge Bob, Flight of the Concords and Jack Black too.  I can't tell you how many times Bob the Builder has helped me with daily life lessons.  Look at Bob and his team: they work together; they all have different abilities and talents; they respect each other's differences!  Or, yes, you do need to learn math!  How could Bob be a builder if he didn't learn mathematics?!   Childishness is to be eradicated. But the state of being child-like? Experiencing joy, wonderment, freedom, delight, understanding? Or like Webster's says: innocence, trust and ingeneousness.  Well, bring that on, I strive everyday to be child-like.