There are many different reasons for a Femdom to use a cock cage, but they all boil down to: power and control.
Cock caging is part of the Chastity kink. Chastity is about abstaining from sexual activity and physical stimulation. Cock caging is about physical restriction for Chastity, but there is also psychological abstinence based on agreements, trust, blackmail, etc.
Cock caging is often used as a punishment or to correct behaviour, but also as a form of ownership or enslavement by the Dominant or Keyholder.
The cage is meant to be a painful experience both physically and emotionally, especially to elicit sexual frustration and push erections into the body. However, wearing a cage can convert pain into erotic pleasure – physical and emotional masochism.
Caging a cock is generally a symbol that the man cannot be trusted to abstain by his own will power.
Short-term cock caging is designed to sexually torment the man, which only increases his arousal and need. After prolonged use, it is known that wearing a cock cage can make a man more docile or attentive their their Dominant. It takes away his sexual ambition making his more feminine qualities shine, and helps him to focus on Her needs, not just in the bedroom, but in life.
However, there is a dark side to cock caging. It can become addictive – the cock cage becomes the Mistress. In long-term use, the physical restraining of a cock into a compact device can reduce cock size and physical function. It also negatively impacts function because of a man’s mental state (he is too used to not being allowed to have an erection or he feels like he is being bad or cheating, etc), and it can take away sexual desire altogether. (However, this is sometimes the goal of Dominants and self-cock cagers.)
Personally, I have only ever used cock cages for short periods of time – max two weeks – but only to increase a sub’s arousal and sex drive. I usually want him to abstain just long enough to turn him into a sexual beast so when I play with him, his energy raises the stakes in our session. I also like to use cock cages as a symbol of ownership – his cock and orgasms are Mine. However, cock cages aren’t usually necessary to make a sub abstain – subs can abstain on My command and will. The cage then becomes an accessory, and a physical reminder. It is also about discomfort and pain. As a Sadist, I enjoy making life difficult for My sub, and wearing a cock cage makes him have to physically put up with a metal device squishing his genitals, making daily activities, such as sport and bathroom breaks, a challenge.
Sometimes I like cock cages to be worn during a session, especially if My sub is a sissy or feminized. Such helps get them into the right headspace, and makes them feel more feminine. But it usually ends up coming off because I want to get off.
I’m a promiscuous woman, what can I say? I love sex. If a man is in a cock cage, and he is being stopped from having sex, it means I’m also not getting any. That’s crazy! Why would I want that? There have been times where cock cages have been used to prevent Me from accessing their cock. One time I had arranged a session with a borrowed sub in Berlin. He came cock caged and I was pissed. This was not the arrangement. Apparently, his Domme was trying to use Me in their play to edge him for her later that night but was too jealous to actually let Me have access.
I know that there are many Dominant Women who put their husband in a cock cage to stop him from badgering her for sex. Usually these women aren’t interested in sex anymore, (or prefer to have sex with someone else). But I require all My personal submissives to be virile creatures, and one of My conditions to be in a D/s relationship with Me is that they become My sex slave. So cock cages for Me are a tool to enforce that.