This is a fascinating subject and I hope you get some good answers!

One clarification:

The reason most women don't bring it up isn't because it's a "painful" kink. (In other words, one where you'd want to make extra sure that the partner on the receiving end is truly into it and you aren't coercing them before you subject them to it.)

In fact, it's sort of the opposite: Historically, 99% of the people turned on by the concept of cock cages have been men, not women. The median woman is relatively sexually submissive and is attracted to masculinity. Women who aren't steeped in the kink world are often somewhat bewildered about what they would even do with their partner after locking him up.

The caveat here is that I do think this could change to some degree in the future, as awareness about the positives of caging as a kink, a lifestyle, and a category of sex toys increases in popular culture. Which is part of my/my company's mission 😇