I think that's the sum of it.
It's The Queen's birthday party, and she wants them all to be around her. That's fair. It's her support system, like her empty handbag, that she carries (though I haven't seen that handbag lately come to think of it. Has she dispensed with it?)
It's not like they are all getting a stipend or honorarium for being out there on that balcony.
I think it makes her feel better to do such a daunting appearance, before so many people, surrounded by those she knows and loves.
Because it is overwhelming (especially for those not egomaniacs) to be before a crowd like that, even after years of experience. JMO.
Yes.
A nice summation of what it might be for The Queen. Less lonely I would think. Like Janis Joplin famously referenced. Nothing more lonely than being adored by a crowd. Yep. For sure she wants connection to her real-world life once she steps off that balcony. JMO.
BTW I think the 'slimming down' oft spoken of is only in terms of titles and salaries, correct? That would not preclude King Charles from continuing on with his mother's twice-a-year family reunions, I would think. Why give up on that, just because of a change in reigns? It seems to me, Charles would want to gather his extended family around him, if only just twice a year. It's a way of thank you, too.
BTW will King Charles have an official June Birthday, too, because of the weather being so nasty in November? Wondering.