I think that if you don't talk with him about it, this will continue to gnaw on you. You'll be watching his behavior with your older daughter and looking for differences. You may come to resent him. If your older daughter had an involved father, this may not be as big an issue, since her bio-father would likely be including her as a beneficiary. But since this is the only dad she has, I understand your need for him to step up in every way and provide for her.
This will be a tricky discussion, but I think it needs to be had. The issue is bigger than a name on an insurance policy. The issue at hand is does your husband want to be this girl's father, in every way. If so, then you can explain why you feel her name should be on an insurance policy. If not, can the two of you come to an understanding of his role in her life that will work for all of you, with no resentment or unmet expectations.
I've been a stepmom for 25 years to two young people. They do have an involved bio-mother, who has not always been a competent mother. My role has evolved over time and circumstances to meet their needs. I have worked to financially support them when they lived with us. They are not in need of my estate, however, since they have very wealthy elderly grandparents on their bio-mother's side. I also have a 9 year-old daughter. She is my sole beneficiary on all my accounts.