To answer the "why" question; well, we talked about it at length. My husband is the least MCP person around, but he really felt that it was sort of like what someone said above; that having the same name shows we are a team. The issue of having kids with different names never came up. I knew plenty of people who had different names from their kids, even in 1979.
We also had the same discussion about having a joint bank account. We decided to get one. Many years later, we ended up having 2 accounts. Although they were both joint, my check went in one and his in another. That way, I could track "my" money, although it was mostly so I could buy gifts and things for people that I wanted to specifically buy with my earnings. Same thing for my son's college education and his car. I was very clear to him that my salary was paying for those things.
I know that this seems very old fashioned to some, but I have never felt like I lost my identity. My husband has done nothing but encourage me in all aspects of life. Those of you who know me in person can probably guess that I am very outspoken and I wouldn't put up with cr*p from anyone. I had a very traumatic and horrible first marriage at a young age. I swore that I would never get myself in that position again. Changing my name hasn't made a difference in how I feel about myself.
Though at one point, when my husband's parents were acting like azzholes, he considered changing his name to my birth name...