A patented invention should be described in sufficient detail, and the description is made public. This is how important inventions do not get hidden form sight forever, even if they don't bring any profit.
This also allows people (including governmental agencies) have an idea of what is being sold as a new invention. Would you take a new medicine whose chemical formula is a tightly guarded secret?
I think that what makes a patent worth it is the first-mover advantage. What makes a patent problematic is a long expiration time which does not depend on its being used productively.
The best idea I saw is an exponential patent fee. Say, first year it's $100, second, $400, third, $1600 (all amounts acceptable even for a lone-wolf inventor), ... tenth, $26M, ... fifteenth, $27B.
This way any useful invention can enjoy a patent coverage for some time, and afford it for some more time if it's bringing in significant profits, but sitting on a patent for a long time would be impossible even for the richest companies. Keeping a portfolio of unused patents would become pointless, too, and patent trolling, likely unprofitable.