The profits are taxed differently because the investor class lobbies for it. That said, if the lower tax rates really do increase and encourage investment then I think that's a good thing. I'm not sure if this is true btw.So that is why you tax the profits differently?
I think estates should absolutely be taxed, because those who receive it do literally nothing other than popping out of the right pvssy to earn it.
If we were to close some of these absurd loopholes that corps and the ultra rich take advantage of, it wouldn't even be an issue. The tough political sell is that those same interests also pander to the high salary earners who actually do get hammered, but don't have access to the same tax shelters that corporations and the uber wealthy do.