Remember, there are two very distinct perspectives here.
One, what you is not immoral, unhealthy, or currently illegal. It's normal to be curious.
Two, I can understand your wife being freaked out by it. A lot of women need to see their man as strong and in control. Seeing you in this position of vulnerability could be a real turn-off for her. Some women are turned on by it, however. I think the applicable term here is "preference." Submission is a common fantasy among women and she may be freaked out by seeing you want to take a submissive role.
Please don't try to pressure your wife into something she's just not into. You might want to try giving her a gentle playful spanking and see if she becomes more comfortable with it, with her consent of course. Some fantasies are best left as just that, fantasies.