It's understandable why both sides would take the deal, in my view. The state needed to take it because of how much time had elapsed since then, and how much coverage the case had gained; the disintegration of memories and maybe even some evidence. It benefited both sides. I don't mean to inject politics here, but I view in same light as the Iran Deal: better than nothing (i.e. released and declared innocent). The fact they are, technically, still guilty, does still keep them on somewhat of a leash, however long.
I guess the biggest travesty of it all is the fact that the case, for all intents and purposes, is closed. I know there have been conflicting reports on if that is truly the case, but either way: the longer this goes, the quicker the state and the police department will simply abandon it as a cold case that will never truly be solved.