The better question to be asking here is if the 300wsm is the better choice for our intended purposes. The shorter fatter case of the WSM allows for a more compact and condensed powder charge. Keeping that powder in closer proximity to the projectile. The shoulder angle is also more advantageous to accuracy and precision. It allows for short or medium length actions and a more compact rifle package.
Keeping ethics and skill level in mind I would say the majority of us hunting long range don't "need" a projectile heavier than the 180s. So if you compare the ballistics of the WM and WSM shooting 180s they are very very very close.
At least for how I hunt...and how I shoot...the WSM is the clear winner here for all but the biggest most dangerous animals (which I don't hunt...ie kodiak bear).
Is the 300WM death? No. Not by a long shot. But for the majority of people out there hunting its hard to justify using it over the 300WSM.