If the house must be cleaned and if the meal must include salad and desert and if the plans must be negotiated and settled upon 24 hours in advance, then of course people aren’t coming over very often and “We should get together” doesn’t mean anything.
But if the house can be messy and if the meal can be leftovers and if the plans can be no-plans, then we can spend all kinds of time together and we don’t have to bother with “We should.”
I’m arriving at the point where I prefer an invitation (both given and received) with vague and unpromising content to no invitation at all.
YoRocko! 
Doesn’t matter how often you tell people to “just drop by… it doesn’t matter when, and I don’t need a warning”… People are uncomfortable doing that. So I finally gave up and opened an Inn. Now people make reservations and feel that, once they have committed to it, they have to come visit. Even though they’re all strangers, it’s nice to have finally figured out a way to always have people popping in…
I am coming to your inn
I’ll believe it when I see it…