I share your concern. Just this morning, I was trying to check my wallet but inadvertently checked someone else's. I was like "Holy shit, I have $3000 worth of steem power!" But then I was let down when I realized it wasn't mine (which is about $9).
Maybe the steemit devs could give us all a second wallet that works more like a bitcoin wallet. I know that, with the bitcoin wallet I have, I can generate a new bitcoin address each time I want to receive money. I don't know very much about the technical details, but it seems like bitcoin has more privacy than steem.