I think part of being interesting on twitter is making sure that you are involved with the right people and those that are a good fit for you. Follow people in your niche, follow people associated with topics you are interested in...make some relevant tweets, send some relevant replies and see what happens. I think the best advice I can give is to just be yourself. Also, if you'd like to follow more people but still not take away from your twitter experience use Tweetdeck to separate your followers into groups .
That's a nice sentiment, but I can't think of any medium that was built solely built for the goodness and well being of the community. Twitter is not defined as only a personal a social network, not even by it's owners or creators, so attempting to label it as that is only setting yourself up for disappointment. All popular mediums are and were created for commercial proposes, My Space, Free Email, TV, Radio, Newspaper, Facebook, and the list is endless. The purpose of creating a large user base is to have masses to advertise too. If some good comes out of it as well, then so be it, but creators of social networks do not invest time and money just so people can have a free way to communicate with each other...they do it to grow a huge base of users to market to. Server Networks, Engineers, Legal, Office Space, Electricity, And Employees all cost money...companies like Tiwtter are not charities and it's employees are not volunteers. With popularity always comes people who will spam and exploit it for their own means, but these things are not created out of some holy purpose for the common good of man kind. If you want a platform that is free from commercial influences, then unfortunately you are going to have to build your own and pay all the bill yourself.