Yes, agreed, but asymetric morphs "out off the box" have become less and less important with the new morph brushes available.
With a the stroke of the mouse, anybody can make a morph.

And Blender is gaining popularity "fast" to create morphs and Full Body Morphs.

"Default" a figure has to be symmetrical for all Poser rooms and tools to work as designed.

Asymetrical morphs, are on the lower list of the workflow.

Poser 1, 2, 3, 4, 5, 7, P8 and PPro2010, P9 and PP2012, P10 and PP2014 Game Dev
"Do not drive faster then your angel can fly"!