"Have a cost associated with a vote. If you vote for content that sucks, you may net lose some infinitesimally small steem power as the reward is less than the cost. If you vote for something that rocks, you net in the positive. This will make folks take their voting more seriously."

There is a cost, an opportunity cost of lost potential curation rewards. Also having an actual cost in terms of SP would heavily reduce the exposure minnows would get. People would just gravitate towards the most popular authors even more so than now.

I'd recommend getting on Steemit.Chat and talking to people on there, there's a post promotion section and you'll get far more exposure than posting here directly :)