A stretch 4 literally means a good shooter you can park in the corner and make defenses pay for doubling on the drive.
But to your new argument, I don’t think Randle’s better ball handling is all that much better. Even if it were, defenses in the playoffs aren’t afraid of his shooting, which means they’ll pack the paint more and dare him to shoot. So whatever offensive gains Randle may offer with his ball handling will likely be more than offset by the inferior offensive spacing.
The only line of reasoning that I can fathom was their thinking was your last point, that they want a strong perimeter defender, specifically for Luka Doncic. I still think it makes the Wolves worse because Randle isn’t really a perimeter stopper. He’s never been named to an all-defensive team throughout his whole career.