The primary advantage of using a larger cell is that fewer of them need to be made and handled during assembly. There is only a trivial density advantage using a larger cells, and a significant increase in the thermal and electrical path unless the design is changed to mitigate those problems.

If your battery factories are already at their production limit, it’s really appealing to build larger cells. They take only slightly more time and space to manufacture, and handling fewer cells per vehicle simplifies every subsequent manufacturing step.

But as an end-user, there is minimal advantage to the larger form factor. Using the same build techniques and chemistry with the existing 2170 size would result in a superior battery.

Finally, you might have the wrong idea about longevity. If you want known long life, you want the current pack design. Experience has shown the current batteries are going to last the expected life of the vehicle with only a modest drop in performance. You should stay away from structural packs until there is enough real-world data to show that flexing the cell casing doesn’t cause physical wear or capacity loss.