but the old roots - a big joyful gathering of the clan - seem to be missing
I can't speak for anyone else but myself, but I've never gotten that feeling at Oshkosh.

I was gratified to find "some" of the old EAA spirit out on the flight lines and under the wings of aircraft (in the shade). I guess it is the "family picnic" atmosphere that is missing.
To me, I've never found a difference between those areas and everywhere else. There are nice people and there are ******** in all areas of Oshkosh. If I'm looking for a "picnic", I'm going to go to something other than Oshkosh. There are plenty of fly-ins and regional events every year to get that "ol' time religion" if you will.

EAA has been described by some as having become too greedy ($) and sadly many of those people have not renewed memberships.
Some people are, to use an adage my grandmother taught me, just like a cat in a room full of rocking chairs: they are going to find something to yowl about sooner rather than later.