The solution is to make peer reviewed code produced for a paper be considered equivalent to a paper in tenure decisions. And for all papers in peer reviewed journals that do computer analysis to be backed up by peer reviewed, published code.

That makes code development beneficial for your career, gives an incentive to not keep it under wraps, improves quality, and is likely to reduce the number of published incorrect results.

Of course that is a pipe dream at this point, but what's wrong with dreaming?