I don't think there is anything wrong with putting importance on the sexual aspect of your relationship at all really. Sex and the intimacy and exclusiveness that comes with it is a reasonably important aspect of a relationship imo. I think if someone didn't feel comfortable with that and wouldn't try and heal that void, I would feel frustrated and hurt.

Some people would see religious faith as an issue that affects their partnership, other's consider financial stability (or loss of) a real issue. If I married someone who then turned T total and didn't like music, I would feel that this was something lacking for me and would try and encourage my partner to have a glass of wine with me and listen to music at certain times, whereas this wouldn't bother another person. Everyone wants a forefilled and compatible relationship and people put importance on different things to feel that.

You seem to have a very happy relationship, other than this, and I am sure you both work hard to be the best for each other and at being good parents too, no doubt. Imo asking your wife to work with you on those things that are lacking for you, is just as important as anything else that affect either one of you. I am not saying try and make her do anything she doesn't want to, but simply to talk to you and think and try and for you both to understand better, is a healthy start. Perhaps agree to some kind of therapy etc.

Can you not fantasise about your wife instead? If you are going to think up an imaginary women that enjoys sex, why not just imagine that person is your wife and fantasise about your sex life with her? x