Long story short, I do and I don't. There's some nuance in there.
I believe my thoughts on this are in line with feminist ideology but let's keep in mind these are my thoughts. I don't and can't speak for all feminists, much less all women.
There's a couple of ways to think about that.
First off, breasts are an errogenous zone. Given that, they can't truly be desexualized and you wouldn't want them to be. They're very important to sexual satisfaction for a lot of people.
When you get down to it, what I really want is to end women's sexuality as a weapon used agsinst them, of which the "male gaze" and attention positive and negative, is a part of.
So, it's not really about the breasts, per se.
Let me give you an example.
If you are a woman living in virginity culture, which western civilization most certainly is, then your breasts become one of the things that make you lose social value over the course of your life. We all know that women with small, nubile, perky breasts are favored over women with larger pendulous breasts. Larger ones are more matronly, right? There's really not a lot of truth to that once you get past the teenage years and have developed into full womanhood, but that's the perception.
Many men lose interest in a woman's breasts after she's had a child. But having a child doesn't end your, let's say, sexual profile. If you were aroused by breast attention before, you most likely still will be and now your mate is leaving you unsatisfied. You're being shortchanged on sexual experience because your mate has a boob hangup. The end result of that is decreaed libido and decreased interest in him because he's making you feel unwanted, unloved, undesired sexually speaking, and like he can't see you as anything other than a broodmare and milk factory any more. This sucks. Not the best welcome to motherhood you could give your mate and not the best way to parent your child or look out for your own interests but that's the way it goes many a time. In fairness, sometimes it's the new Mom with the hangup and if the man feels neglected or rejected because of it, then problems with sexual satisfaction will also arise.
That's all barring legit physiological issues that are usually temporary, like tenderness. I can testify to that. Whew! Who would have thought that lumps of mostly fat and connective tissue could cause such pain and agony? It doesn't seem logical. But I'd rather go back to full end labor than be in pain like I was once my milk came in again. It was unpleasant, I'm telling you. Definitely some "if you touch me, I will kill you" vibes that I cannot guarantee, even in retrospect, were completely hyperbolic being thrown down.
There are lots more examples. As for the reasons why, here's a few:
I'd also like to be topless without being hassled, harassed, or gawked at. Not all the time, not everywhere. Imagine trekking through Yellowstone in Blue Jean shorts and boots and your backpack though. During the day. I dream of such things. Imagine sumbathing in the desert the way we sneak off to go moonbathe.
I'd like to be comfortable in public braless. Bras are a pain in the ass, well...tits. Push up bras should be classified as torture devices. Why? Just why?
I'd like to see fewer women who hate their body. That's not a huge problem for me though some body dysmorphia hits all women born post WWII at some point. I was able to deal with mine but it wasn't severe, I had help, and frankly, I never wanted that straightjacket in the first place. I've been balking against beauty standards and being turned into a living doll since day 1. As my mother will happily tell you all about in long suffering inglorious detail. Most women deeply struggle with body dysmorphia though due to marketing propaganda. All that is centered around the male gaze and you all are heavily propagandized with it too.
Less money needing to be spent on the womanhood penalty of having to buy woman gear.
The nonsexual but physically sensual pleasure of feeling the breeze caress ones breasts. Or the sun's warmth. Or the rain. Ooh, snow. It actually doesn't snow here, but imagine. It would be so much harder to talk myself out of going on vacation if I could be topless in the snow. You know?
I guess all this kind of stuff can be filed under a larger banner of "for the freedom of it". We've cut ourselves off critical contact with experiencing the natural world and this ourselves hiding from and pandering to male lust rather than punching or tazing you men in the nuts as you deserve to check this behavior. It's male bad behavior and we agreed to punish ourselves because of it.
I want my freedom.