Im not having too much trouble with the Bright red and other geometry default colors. But the color choice is a leftover thing of Max when the old UI also made use of bright red icons. It would be more consistent and add a subtle touch of style and give Max more personality to have its typical colors like that Turquoise, Yellow Orange, Light Gray already used across its UI to be used more to display geometry (like sub-object selection). The Object selection outline is already Teal color so this will also add to the coloring consistency. Also, if you look at some tooltips, they already start to make use of this teal color.
There are still old icons using that red color waiting to be updated. The red color sub object selection is a remnant of this old design