Partner saver tickets can be worth it. I was comparing some NH J tickets and it was a much better deal to transfer and use MP versus doing the conversion/purchase with Chase. Now with the dynamic awards on UA metal, that is another story, but the dynamic pricing is much more recent so in a historical sense they still could have had a lot of people transfer. Only Chase and UA really know.
If you are looking to redeem NH J, it may be better to transfer from Chase UR to VS (Virgin Atlantic) and redeem NH flights from there. The redemption would have to be roundtrip but otherwise fewer miles required than UA or NH's own FF program.