You might argue, "That'll dissuade investment!", but when $17 trillion in negative yield bonds [1] (a third of the bond market) are communicating, "Hey there, not a lot of investment dollars needed kthx", that argument falls flat. Your investment dollars aren't needed. There is nowhere productive for them to go. So why have public policy treat their income differently?
[1] https://www.bloomberg.com/graphics/negative-yield-bonds/