For congruence's sake. I'm not particularily fond of the design myself but it still is a design choice author made. No matter how minimal you may think the impact of such a change may be, it still is a change from someone who doesn't have any right to do so. It may seem unreasonable but consider the alternative: how many such little change can you really tolerate before the story becomes unrecognizable ?
I originally started this story as a LN. So I had no frame of reference what any of these characters looked like besides the descriptions that were noted in the story to which it was left up to the readers to visualize. So when it became a manga, that was the author giving it form in which they gave their stamp of approval to what their character designs would be.
However the original case here was the supposed complaint about Panamera's cleavage being shown (fully drawn out by the redrawer). It's rather silly to be upset about it. If anything they should be taking their issue up with the redrawer who helped in the translation of those chapters rather then airing their grievances in the comment section. As previously noted, if they really wanted to see female mammary glands then there are plenty of places and easier ways to do it.
