Some (potentially relevant) previous discussion: Clarification on the mapping of bathing places
(personally I think it makes sense to separate the natural feature (natural=beach, though I’d be, on principle, alright with natural=sand/etc. as well) and what humans make of it (leisure=*), it’s after all easy to double tag and as was discussed in the above topic the second meaning helps differentiate between “could you use it as a beach” (might be awesome looking sand and water, but unknown to you there are dangerous currents) and “should you use it as a beach”)