Why did Josh act more like a toddler than a 12-13 year old?
Don't get me wrong, this is still a classic 80s family comedy that mixes some sentimental serious moments in with it, but it always bothered me how Josh (especially AFTER he's in Tom Hanks' early 30s body) seems to act like a 6 year old, not someone just becoming a teen. Like how everything in his apartment is like a playground, and he never really does anything exciting once he's in an adult body. His friend Billy seemed a bit more typical though.
(I'm 30 now and born in '81, so I grew up in the 80s only a few years younger than Josh. I knew some older kids and none of them acted that childlike, either did I or any kids from school or my neighborhood back in 1994 at this age.)
Fred Savage in "Vice Versa" was MUCH more believable to me. Charlie was only 11 and he acted older/cooler than Josh (far more accurate to how I remember kids being then). Sure he still had some childhood aspects, but was also a hard rock fan who liked playing drums, and just generally seemed more adventurous.
Did Penny Marshall really believe 12-13 year olds were still that innocent and naive? It just screams "Baby Boomer screenwriter who grew up in the 50s and was totally out of touch with how kids acted in 1988!" to me.