Nintendo's decision to reduce the price of first-party digital titles does not automatically carry over to third-party publishers.
That's fair, all of what you say is fact, I'm in agreement.
My point is data must be present in the cartridges in some shape, way or form, I put convenience above all else.
The NS2 has solid third party titles in their line up, the best they've ever been as a matter of fact; so being able to have the data extracted from a slow "write-only" cart is preferable for me, than re-downloading the same game over and over in case of a storage limitations (multiple non-digital gck), or airport scenarios.
It is policy not to spend an extra $5 for S1 tech, limiting methods on how data is transferred to the system restricts user flexibility, which is imperative.
The current offering works as an incentive for the user to spend more when titles are bought, which fair, that's the whole point; but if money isn't the issue then availability is, even if the SD Express can simply be upgraded, the amount of available faster storage in the UFS is more finite; games like star wars require an install there, and these UFS only titles will grow.
Therefore, mandating cache carts for extreme scenarios would be a great addition to at the least quickly manage storage.
The S2 console has the ability to implement this, extracting the files into UFS in first boot, installing the critical assets from cart, and reading that data to the user in the same beat, allowing near-seamless streaming from UFS, with possibly no internet required if compression shrinks the .nsp enough.
Heck, this should be a feature for any physical game, for that internal speed boost.
Sony and Xbox have done this with DVD's to HDD for a long time.
It is time for Nintendo to take a page from them and perfect their method.