That formula gives some very low wpfs - only 406 total_wpf @ 18 agi, 6WM, instead of the current 580.
If you like simplified formulas though how about
total_wpf =15*agi+55*WM
You can't directly tinker with the total wpf formular. You have to change the deltas instead and the new total will result from that. What can be done is that I parameterize delta wpf WM and in a similar style delta wpf agi.
So then we have:
wpf_0
delta_wpf_WM=a+b*WM
(currently a=20 and b=10)
delta_wpf_agi=c+d*agi
total_wpf=wpf_0+sum(wpf_WM)+sum(wpf_agi)
total_wpf=wpf_0+a*WM+b*WM*(WM+1)/2+c*agi+d*agi*(agi+1)/2
total_wpf=wpf_0+WM*(a+b*(WM+1)/2)+agi*(c+d*(agi+1)/2)
You can then freely choose wpf_0, a, b,c and d for theorycrafting.