Since when there is any surgery they always cut at least some nerves, and right now they can't repair that, I presume that hole doesn't have much in the way of feeling. Possibly none. And with all those other surgeries done, fake breasts probably don't have much feeling in them either, and if there are more modifications - even more nerves cut, and more skin that can't feel anything. So they are cutting off what does make sex feel pleasurable in the first place, the ability to feel somebody else caressing you.