Umm, yeah. I can't believe how many of you have separate accounts. If you have them, then you haven't found the right SO. Just saying.
I think it's a function of people getting married later in life than in prior generations.
Back in the day, you got hitched in your late teens early twenties. It made sense to combine everything, as you were just starting out and learning how to do it anyway.
Now, people are often in their thirties when they marry. They are used to managing their own stuff and buying what they want when they feel like it.
I favor having a joint account. The parties discuss how much each should contribute to cover the standard monthly nut, plus incidental expenses.
The rest stays separate.
This assumes both spouses make roughly the same though.
I had a friend that had a joint account only. He made a large withdrawal to buy his wife a surprise for her birthday or something. Expensive jewelry or some such. She freaked and was considering hiring private investigator and attorney. Ridiculous.