Quote - "The more definition there is in a base model, the harder it is to morph it out."

Sorry, wrong.
It's easy to smooth a well defined mesh, but it's very hard to get definition in.
M2 has the best muscle definition in Poserdom.
Yet Stephanie 1 is EXACTLY the same mesh.

you missed the point completely here, sure its easy to smooth out a mesh to create a completely new mesh, but try combining morphs that change the shape, such as facial character morphs, on a base mesh that has a lot of detail and you will soon find the limitations, that each morph needs to fight the base mesh shape to create a new shape and when you combine two or more of those morphs you are basically multiplying that shape correction. thats why starting with a simpler topology but more well thought out mesh flow is always going to give you a more versatile
mesh.