You can become a witness yourself, have a vision about Steem that resonates with the community and demonstrate your good intentions towards the platform. If you can voice your opinions, ifyou get enough votes, if you can muster the time and financial investment it requires to be a great witness... Then you will be directly part of the decision making process.

I don't have the time or the expertise for that, so I vote for those witnesses I trust that can voice my opinions even better than I can.