I think the backrooms were awesome but that was one of the main issues causing the server to crash or lowering FPS, so no I do not think they should be put on the main map sadly
I would like to see maybe something like the underground parts of bases being added onto the main map, things like that are just something different then the boring old map we have all been playing for sooo damn long. Other than that I would just like the map to stay the same. As I mentioned the back rooms were dope but caused way too many issues with the server. And the rest of the stuff was more just Halloween decorations to make it kind of "spooky" so it wouldn't make sense to have those types of things in the main map.
BUT I do think that the main map overall should be updated. I know too many people are against a whole new map so I don't see that ever happening (or at least any time soon) but I would like to see changes made just because I and so many others have played this map for so long it gets boring to me. I know every single inch of the map there are no more surprises, hidden areas/bases, or anything to explore. Maybe just make it a little bit larger and have a few more streets with base or shop type buildings. Or maybe extend the part of the map where a lot of trees & rocks spawn by the underground mine. Or add something to some bases making them different, larger, extra rooms, underground areas, etc. There are a million different things that could be done to the map to make it better or at least just different.