Infrastructure isn’t free. Happy to donate to Wikipedia on a yearly basis. And the emails are only once a year.
Because the initial mission is still, by and large, done by volunteers and unpaid editors.
Wikimedia is a bloated leech
This year I've had three (two in September, both from donate@wikimedia.org, and one from jimmy@wikipedia.org in October saying 'We've had enough').
They're very firmly on my "do not give money to" list, together with Mozilla (donations go to everything EXCEPT Firefox development, which isn't made particularly clear when you donate, and much of their other stuff isn't worth supporting IMO).