Inspired by this recent question
What would be the balance implications of allowing all natural weapons to count as monk weapons (for the purposes of enabling the martial arts feature)? I am aware that it would be a straight power increase for the class, but am unsure of the extent of the increase and whether it could be acceptable.
Though the major application of this would be for a Monk/Druid multiclass, there may however be other less common interactions that could be problematic balance-wise. Ideally answers would address these as well.