Seems to me, I paid a lot for some SP, so I want to use it to my advantage, when I take the time to read other's work and comment on it... if I feel I have put in a lot of time, I want to be paid for that time, to contribute my focused attention on the community. It feels fair to me.
And it's an entirely different thing, a different part, of steemit.
There is posting, then there is commenting and curating, they all get paid out based on different metrics.