So the problem is that all unearned income that isn't for tuition is being taxed the same, regardless of who it's coming from and who it's going to? Am I reading it right?
I am all in favor of cutting taxes on unearned income. However ironically, those most opposed to that also like to complain when it’s their unearned income being taxed as in the case of a stipend or fellowship.
It's also usually NOT a rich parent. For example a big funder is NSF or NIH, these institutions grant money to labs with the expectation that they will perform research.
Don't think of it as being paid to go to class, think of it as a job where you work 40 hours a week (usually way more) doing reserach, then go to class, then on top of that help teach those classes through being a TA.