I don't know whether it would be desirable to tie investments to outcomes, for several reasons. Nevertheless, measuring outcomes is eminently desirable. If it's to identify best practices and attempt to adapt them to other circumstances, then I don't see how measuring actual outcomes could be a bad thing. The problem likely resides in the measurement of these outcomes, particularly in health. What needs to be measured, and how do you measure the outcomes? That's a question I'd rather leave for others to answer.
In any event, I believe that measuring outcomes is definitely worth doing.