"So is there any significant difference to cutting out the sand bar as opposed to tagging the park area as "beach"?"

Marking the whole park as a beach is inaccurate because the whole park is not a beach. It's akin mapping an entire school as a cafeteria just because it has a cafeteria somewhere on the grounds.

OSM Generally works on the idea of "One feature, one OSM element"

You've also extended the beach down beyond where it actually is. Even on very, very current imagery, the beach does not extend as far as you have moved it. Can you explain why you are doing this? Scrub going almost the whole way up to the river bank.