In the FC I am in, the FC members often gather around nearby the FC house and the Market Board.
But that said, the neighbourhoods concept will only truly shine if the entire FC is filled with active FCs with active members, and not FCs with min. (4people FC) just to grab a house in the FC-only wards.

I think RP communties use them more though, famous RP venues always have long queues.

For my personal house, it's just me and another friend hanging out there since we have MB and summoning bell, and as a quiet spot to do daily roulettes and to chill.
The plots around my house are like abandoned houses, so inactivity is also a problem.

Maybe once they enable the auto-demolition timer, and set it to a lower duration, perhaps it might help in encouraging more socialization in these "neighbourhoods"?