We probably should have kept him but that's because we had so few options for us to cover that position but not because he'd "proven his worth here continually". He actually proved the opposite AFAIC and I'm surprised there are so many posters here that recall his time with the Suns differently. He was like Ayton - showed great occasionally but let us down far more often than not.
My guess, based on his time with the Suns, if we'd kept Payne he would have missed 20 games, stunk it up for 30 games, played well in 10 games and decently in the other 12 or so. That's noticably better than any of his replacements have looked so yeah, we'd be better off with CamP. I think he would have made a difference in a couple of our 4th quarter collapses but I don't think any of us would be feeling confident about this roster even if we'd kept Payne.