i’ve always thought risers make no sense from an engineering POV, you’re better getting the height from the stem and keeping everything straight (you can also use a long fork steerer but that’s slightly worse as longer path). that said, i run risers because i have an older frame and need the position, very few nice high rise stems around (Hope 25deg is one). also a riser gives a protected area in middle of bar for gubbins when you flip bike over or crash.
so risers are essentially a bodge fix for a frame geometry problem.
ideally, if you could custom make a frame for yourself, you want long steerer tube and the top of the steerer where the bars go?
note: all above is my own uneducated thoughts and could be bollocks.