Light piping is an expense that gets them little reward... Who buys a toy because it has light piping?
And how many don't even know it is there or cares if it has it?
It was a nice gimmick when it first came out, but how do you make use of it?
On probably one toy in six months the light will catch it and I'll have a one second moment of, wow that's interesting... but then the moment passes quickly, and I never look at that toy's gimmick again.
If the light piping could pay for three more paint apps, that everyone can see and benefit from, I'd say ditch the light piping.