I would think having a happy wife would be a great benefit. I know that when I was in NRE, I was much more giving to both of them.
One of my men is much less into sex than the other. He's quite happy for me to be satisfied that way elsewhere, so he doesn't get yelled at because I'm not getting laid.
I also have much more tolerance for when either of them is bitchy, or behaving badly. Because I know I'm loved, I don't worry as much that I'm not, so I'm less likely to freak out on either of them.
Disclaimer: I've never been a wife (nor had one), so I don't have that perspective. But I see benefits.