There is an epidemic of family estrangement today; much has been written about it. It's become very fashionable to be "just our little family" at times like Christmas, and other times, despite the fact that the nuclear unit is how it is every day of the year. These family trends make me so glad I didn't bother with all the expense and sacrifice of having children. My generation is so, so selfish towards their elderly parents. There are echoes of it on this thread from some pp, but mostly I've seen it IRL over and over with my peers. I'd almost say it's normal now for people to not bother with their senior parents, which I think is a disgrace. There are lots of cold attitudes towards grandparents and other family members expressed on MN, too. ETA: And the thread yesterday about the distant DD cancelling her Xmas visit home last-minute had lots of people saying how their unmarried kids didn't even bother coming home for Christmas at all for about five years in a row. I think that's just awful.
If this is the way our culture is going, with parents frequently being locked out of their adult children's lives, or kept at arm's length from them and their grandchildren, then I'm glad I didn't bother. After all, I can't see the trend reversing, since today's children will be learning from today's parents and will be experiencing less time with extended family than previous generations. People are turning their backs on extended family, often for imagined slights and just from pure selfishness. I have seen some truly callous behaviour IRL towards the very people that nurtured and raised them and loved them deeply, including people who were not there for their parents when they were old and ill. There is a LOT of it about.
Some day, the parents of today will be old and quite possibly alone, and they wouldn't like to be excluded from their family's lives. I don't know how that doesn't occur to them as they go about doing the excluding today. Many people's spouses die in their fifties and sixties, and where will you be then, when your children are adults, if you never modelled the importance of extended family to your children? No one wants to be old, alone, and held at arm's length from their adult children and their grandchildren, but many people are doing that today and doing it to parents who loved them dearly.
(I know the OP is having her MIL round at 9 anyway, I'm talking about what I see IRL and the echoes of it that I read on here.)
Seems to me that there are a lot of people in the world who could do with reading A Christmas Carol.