Yes, with ML models, you often can be better off trimming down your sensor data. Usually though, you don't remove entire categories of sensor data. Even when you do, to be confident in such a move, you need to first achieve a working model with whatever data you have, and then through refinement you can prove that whole categories of data are more hinderance than help. They haven't done that.
It seems quite clear that the reality is a full sensor array is just economically non-viable with their business model, and that's framing their whole thought process.
Because they promised FSD back in 2017, they can't acknowledge that going without those sensors means it's going to take them much longer to achieve FSD. Because of safety/regulatory oversight, they also can't acknowledge that going without those sensors means there will be additional safety risk.
So they're stuck making these rationalizations that everyone in the industry knows are at best half-truths. No doubt, at some point we'll figure out how to do self driving with a much more limited sensor package, and when we do, we'll achieve a significant improvement in the cost effectiveness of self-driving.
In the meantime, there's a lot of "rationalization" going on.
Ultimately the only requirement is that the system is safer than humans by some margin that people are comfortable with buying such a system. If that amount is even as little as 2x safer than humans, we still have a moral obligation to roll that out even if we could be 5x safer if we had another $50k worth of sensors and processors on the car.
And all this only considers first order effects. If a 2x safer FSD feels more dangerous that normal driving and thus reduces FSD uptake for a decade, doesn't Tesla have a moral obligation not to release it to preserve the perception of safety of self driving technology?
This mindset is something I see a lot, that “best” means the technically optimal (or sometimes just personally most convenient) solution to the specific problem that they personally are working on. If they take a step back and look at the bigger picture, the technical merits are usually only a tiny part of the whole decision.
Why not have a thousand sensors if more is better?
We really should be focusing on what is the best solution and trying to solve price issues through existing techniques e.g. economies of scale, competition, miniaturisation. Instead they are trying to build whatever solution they can that fits in a pre-defined cost window.
Except this isn't a new phone or sneakers we are trying to take to market it's something that will directly impact people's lives.