In the past, in most European societies, women always changed their last name when they got married. This was never questioned. But nowadays, it has become optional. Hyphenated names were used for a while, but now it seems that an increasing number of women simply do not change their name.
This may be for economic reasons as much as cultural ones. Our society has become much more bureaucratic over the years, with the result that changing one's name is more of a hassle than ever before. I have heard detailed complaints from a fellow grad student of just how much work was required to change her name. She was talking to another grad student, who got married later and decided not to change her name.
Of the five women I know from school who have gotten married in the past few years, two of them decided not to change their names. There does not seem to be any social pattern to this. One who decided not to change her name was a die-hard libertarian, and the other comes from a fairly traditional farming family.
Maybe there are some women who change their name because it is expected, but increasingly the only relevant consideration seems to be "Do I like my husband's last name?"
I have always thought that the ideal pattern of naming would be as follows: Nobody changes their name when they get married. Daughters inherit the last name of the mother, and sons inherit the last name of the father. This seems logical; everyone has a chance to continue the family name and nobody has to do any paperwork. The only adjustment would be that we would have to get used to siblings with different last names, but there are already a lot of families like that anyway.