Culling might not make a difference in the genetics of the area BUT, let's say there's 20 bucks, 10 of them are EIGHT POINTS, you kill all those (ok, this won't happen BUT making a point) and leave the others that have more points- for several years your MATURE shooters will then be the 10's and 12's, etc you let live.
If it were me, i'd shoot a heavier weighting of 8 pointers, I'd improve the nutrition (which you are probably already doing BUT I'd do more mineral licks and year round food sources) AND kill some more does to ease the stress, etc. Just my opinion. *Everyone I talk to seems to have a big amount of 8's BUT the crazy amount of point bucks ALWAYS seem to surface.