Well I do vote for my self on my posts (and rarely a weak vote on a comment to move said comment to the top when pointing out spam/plagiarism/false information). I honestly don't know if this is right or wrong to do, but it does allow me to keep accumulating steem power. Which then allows me to vote on more content in the science/tech tags to allocate more of the reward pool to those areas which I think are important for steemit's future growth as a platform.
You have some interesting analysis of the situation here. I agree that not all self votes are created equally, and spammy minimalistic content which the author is flagrantly self voting on should be considered in a different light from that of good content. I mean nobody is forcing anyone to vote on content they think is overvalued, and as such if the self voter is raising the value of their post too high, the community at large can pass on it, effectively rendering the self vote value less (as they are not receiving any additional reward then had they not self voted, and the community voted on the post.)