You know what, feminism is about women HAVING A CHOICE in what they do. And many women CHOOSE to take their husband's surname. Why do they? For many reasons. Whatever the reasons, it has nothing to do with anyone else!
No, feminism is not about anything so banal as 'choice'. It is about the context in which those 'choices' are made.
If it's all about 'choice', how is it that the majority of women 'choose' to take their husband's name?
Yet virtually no men 'choose' to take their wife's name?
After all, just as many men have those ugly, difficult to spell, unpronounceable names women here are inflicted with.
And just as many women will have those lovely, easy to spell, poetic sounding names they're so eager to change to on marriage.
This isn't about anything so simplistic as 'choice'. If it were, equal numbers of men would be changing their names on marriage, but in reality, almost none of them do. And the reason is very obvious, as @NaughtyBoyGeorgeMichaelJacksonBrown has suggested above. They don't want to be humiliated by giving up their own identity in favour of a woman. Many women, however, seem to be quite happy to do just that for a man. So the 'choice' is made in a very specific context, and not one favourable to women.