Point A makes sense and has been mentioned in the past.
Point B is rather interesting, this map is actually based on a very old map design I made many years ago, and in the past it did have easy to pierce walls in that area, it is not really a camping spot and it was a very dangerous position when originally it was thin, it was 3 or 4 pixels thin and was a straight line that had a thicker ending, that later was removed and finally reworked in how it is, exactly for the deathmatch reasons.
It was a terrible spot (and still sort of is), while from bellow you do have an advantage, that is a consistent pattern across the map and in general PB2 as a whole (grenades are very relevant towards this), it is still easy to rush in but I believe it makes the map a bit more tactical and slower than other sniper maps like stryde-sniper where you can easily just rush positions like that without much thinking and with less need for skill, originally it was like that with people spam shooting it, if I am not crazy when someone was reviewing it for approval they mentioned that the platform was possible to be pierced (it was something like this
https://prnt.sc/Ys5IQ9ARsK9I) and they did not believe it was good, and I agree.
About point C, what even is bullet symmetry? the reason that platform is there is to not allow the long line of fire betwen the two sides and allow rushing in in a slower way that is not completely an all in, which is easily countered by grenades but not by shots, if that was removed the map would trn into a spam fest, something like the middle of x death-realwar and it would be unplayable, this is relevant towards point D.
When it comes to point D, I heavily disagree with it, having playing the map many times over the years and having up to 8 players, it is definely playable and much less of a mess when compared to a map like stryde-sniper, which by itself is not wrong or bad, just a choice of style, the reason being there is a general lack of long lines of fire that allow for lots of frustration and basically randomness when it comes to combat, you can keep track of where you are and where people are coming in from and think tactically, getting harder and harder the more players present, even places which are more open and up to this kind of awkward situation, like the top area, can work since its rahter obvious where are the shot groupings and it is easy to rush using cover considering the specific way it is, also teleport grenades are very relevant here in a COOP mode.
But since your complains are more focused on DM, it is how it is mostly played in what I've seen and basically the same applies with more emphasis on grenades, if you opened the map and made that platform thinner it would only make it worse, considering C would make it extremely open and thus spammable and random and not skill based (also would destroy the map in COOP, again, basically turn it into x death-realwar but with snipers, but the side platforms would feel much less dangerous and thus people would move more towards the middle-top area which would just turn it into more of a mess.
The reason I believe the map works in DM even with 8 players is that it is either very fixated in gameplay, or very fluid as in everyone is moving, it depends on how they play, both styles often crash in DM creating an akward but easy to deal with situation which I enjoy and I think is perfectly fine.
Point A is valid tho.