It seems to me that the requirement to list assumptions for basic sensory data (absent a strong prior as in e.g. "I swallowed a strong psychoactive ten minutes ago") is rather pointless.

It's not clear to me why you think this. Repeating it every time is tiresome, sure, and so that's why the assumptions should be implicitly stated rather than explicitly stated, unless explicitly stating them helps in that situation.

But the central claim is that "all data is theory-laden," which is an important point. It applies to what we perceive "directly" just as well as it applies to the chemical composition of photographs of distant galaxies (to use David Deutsch's example), and so I don't see how a Johnsonian objection would apply.