Real life is chock full of things that "don't make sense." The real world is freaking bizarre.
Dragons really aren't "reptiles." Going by the art from most of D&D history, if they were going to be related to ANYTHING real they're probably synapsids or from the same branch, which puts them between mammals and reptiles. There are mammals that lay eggs, and reptiles that give live birth, and billions of wacky combinations have come and gone inside and outside of the known fossil record.
There just isn't even the vaguest hint of "science" behind these arguments. There is at best "what feels right" to specific individuals, which is valid! but not based in anything but opinion and personal history.
As such, the decision comes down to "what is good for the game?"
The game should definitely not be socially irresponsible and alienate a portion of its audience, so dragonborn women becoming a go-to fetish object for the art team is just an absolute no, but that only eliminates lady dragonbornporn all over the place, which wasn't likely to be considered by the art team to begin with, so that's a non-issue here.
The notion that breasts are inherently sexual or objectifying, rather than just a normal thing people need to get over and stop treating as less normal than male anatomy... is not the most popular view in feminism. Discussions are usually more about rampant imbalanced sexualization of women and their body parts rather than the existence of them at all. You can in fact draw breasts without them being for men or for objectification - fantasy just has a really sordid past of failing to do so.
Given that, it comes down to "what will make this better for the largest number of players." There are plenty of people whose "what feels right" is definitely not "dragonboobs," and that is perfectly valid. There is no inherent "wrong" answer to the notion, either way, so it's in itself just as good as the opposite view. Plenty of people are clearly more comfortable with either position. That said, there is some evidence (though I'm not sure on the statistical value) that a significant number of women are more able to identify with a female character that has secondary sex characteristics identifiable by human beings without careful research. I don't know if this is factually correct, but given my discussions with other feminists have often included how tired they are of the human male form being considered the natural "default" while the human female form is an altered version of the male form... I'm inclined to believe it until there's a good scientifically-rigorous study to figure it out either way. Overall, this means that the presence of breasts (and other secondary sexual characteristics, like build) may make it easier for more players to get into the game, particularly those who have historically been treated ...imperfectly... by the fantasy genre and RPG genre.
There are absolutely people of whatever sex or gender who will have a dislike of them for whatever grounds, and those preferences are legitimate. But, overall, I can't really see a reason for WotC to NOT use more human forms here. That said, it may be useful for WotC to kind of hit the middle road and keep dragonborn and the like -subtle- in these features, perhaps so that players can easily mistake it one way or another. That may be a bit cowardly, but it might also keep even more people happy overall.... at least until the "Are those breasts?" threads start up.
