I have never really considered it "not done" as someone mentioned in the previous comments: it's the default setting for posting.
I don't see why we wouldn't, since it's made possible to upvote ourselves why should we judge it negatively? I think as a community Steemit is a very generous one and I believe its users will continue to mainly upvote others, but why shouldn't we also reward ourselves as well and give our own posts a head start? I don't have much of an issue with it, but then again I'm a newbie so maybe more seasoned members of the community feel differently about it?