I had already planned to change my full name before I married. It had been my plan since I was about 8 or so. I spent a lot of time when I was bored at school writing out new names.
When I married, I was an 18-year-old immigrant who had concerns about being found by my birth family and worried about how it would look to the Home Office to be on a spousal visa to change my name in any way that might seem dodgy.
Replacing my birth surname with my spouse's was the easiest, safest option - though I do often joke when I see horrible surnames in credits that I'd have pushed for a change at the beginning even if I had to take the risk a bit longer rather than be Ms Cock for example. It's a fairly beige name so didn't have those concerns then.
By the time that was all done, I had ILR and we considered picking a new name together when I went to change the rest of my name, my BIL was terminally ill and had feelings on 'losing' the family name - we didn't want to cause unneeded stress at a difficult time.
By the end of that, we'd lost so many people in just a few years, it's only ours now, at least of those we know. All the names we'd considered while waiting were up our maternal lines, but there didn't seem much point. I had the feeling that my current surname is just as much mine as everyone other names I've chosen to take on, we'd already made something new all those years, I didn't need a new name for that at this point.
Around that time is when I learned that as much fun as it can be to discuss theory, fitting the complexities of an individual life into an ideological structure is too often just a stick to people with and rarely looks at the structures that incentivize those choices. The original reason was fitting into a social norm for fear of the government throwing back to another government that had failed for years to protect me from those in the community who had power over me. Keeping the name my parents gave me and giving that to my children wouldn't have fixed anything.