Why do the majority of women still take their partner's last name?

Back in the medieval ages when a woman was married to a man, they were basically considered property for my understanding and treated like an extension of the man's person and family. So it was customary for women to take the man's last name since they were being joined to his family. But now here in the 21st century women are fully independent and last names don't really seem to mean much of anything. I mean what is Smith or McGregor or any last name really mean anymore? Especially in the digital age, lots of people have digital usernames like SarahSmith1727373. So the last name clearly doesn't mean much anymore.... Which leads me to wonder, why do the majority of women still take the man's last name? Especially when some of them have a horrible last name? I have seen some butt ass ugly last names recently, like Fink, Weimer, Slotsky/Slotsky, Hiscock (no joke this is a last name), Hardman.... And then you hear the woman's name and it's like something way more reasonable and less stupid sounding like Kingman, or Harrison, Walls, etc.