UFC's Dan Henderson: Jon Jones Should NOT Fight Brock Lesnar, Here's Why

UFC fans are hurtin' to see Jon Jones fight Brock Lesnar next ... but Dan Henderson is stompin' out the potential superfight.

Why? Hendo told TMZ Sports he's got ZERO interest in seeing Jones vs. Brock, "because it's not for anything, other than for fun."

In other words -- it'd all be for entertainment, a la Mayweather vs. McGregor ... not like the good ol' days when all dudes cared about was stackin' belts.

Henderson would know -- he's one of the most decorated champs in MMA history.

The legend did give Jon props for his comeback -- where Jones brutally KO'd Daniel Cormier to win back the light heavyweight championship ... and then put Lesnar on blast.