why the ending was actually perfect

I'm not a huge fan of cliffhangers, and being a sucker for closure, this one has always irked me. But, the more I think about it, this was really just the perfect ending for the character of Ryan.

Because no matter how many bad guys he catches and puts away, or kills, there will always be more, and, in spite of his honest intentions to do so, promises to others, legal orders from others, he's shown time and again that walking away from the case isn't who he is. With Joe and Theo dead, his personal stakes in solving the next mystery are comparably low to previous points in the series. Plus, with Gwen pregnant, his personal sacrifices are comparably high, which he abandons in pursuit of the cause. Plus, as an audience, with Joe and Theo dead, we learned just enough about the next bads to be intrigued (and admittedly confused), but we're not so invested in them that we crave the closure like we would had the show ended with Joe still on the run.