When my parents got married, they merged all their finances together into joint accounts. Every single account they ever got was always joint ownership. But our predicament was a little different. My mom said he didn't know how shit my dad was with his finances and how little savings he had. Made sense, my dad was buying $30 undies (in the 1980s). Because of my parents, I always thought joint accounts were the norm.
I asked my girlfriend (who I've been living with for the past several years) and she said we'd probably have a single joint account for shared finances and maintain a personal account - not that I really care. Having your personal account means the missus can never bitch about the useless shit us men buy