With a 200 grain premium bullet the .300 WM is at its best. I miss the 200 grain Swift A-Frame Remington used to load in its Safari Line of Factory ammunition. Federal used to offer a 200 grain Nosler Partition in its premium load. The reason I use a 300 WM instead of a 30-06 is that I can use a 200 grain bullet at about the same trajectory as the good old 30-06 does with 165 or 180. I don't need the extra range, I like the extra punch of those heavy bullets within the same range. I like heavy bullets. I also keep my shots within 300 yards. Thus the preference for heavy bullets. My friends like to shoot further and choose lighter bullets. Each to their own.
I am not as near the experienced hunter as many on this board. My personal experience is that heavy for caliber bullets do a good job for what they are asked to do. I may need to hunt closer than others with long range set ups, but 300 yards is within my range with my heavy bullets.
I'll likely go back to Africa for a plains game hunt with my .300 WM, ( I really want a .375........Holland and Holland.)
Everyone have fun hunting.