The Bathyscaphe on a bracelet is a few thousand more than the Mariner (date) but with that comes a feeling of less compromise on the quality at least as far as the movement goes. I definitely agree with of your points and I'm not trading my Blancpain in for a Mariner any time soon (ever) but without a personal attachment to the historical Polaris lineage, I think the Mariner looks great. My context is limited to the existing Polaris line before the Mariner which was much to conservative for me, this feels contemporary and exciting. Additionally, the improved wr rating and attempt at making the crown more functional with the markers is at least giving a nod to technical competence that was missing in the previous Polaris watches. Taken for what they are I see where you are coming from and agree but the fanboi in me sees this as a positive step forward (from a design perspective) for JLC towards making things I might be excited about, even if they are still catching up and there's a long way to go.
What I'd really like to see is JLC level up and compete with Blancpain and AP divers. The Mariner is a half step in that direction from the Polaris watches, I will be curious to see if they continue to go up market or stay where they are which is a compromise on quality and price between Rolex and Blancpain.