The point I wanted to make is that the assumption that preferences do not change is not warranted in general. Thus there is nothing irrational about making different decisions at different points in time if either preferences or other boundary conditions have changed, or based on new information that is gathered along the way. On the contrary, that sort of adaptation is perfectly sensible and has a solid basis in statistics and decision theory.
If you say "a photographer who did not want that sensor last year because she was happy with the colour and tonal subtlety of her images has no reason to want it this year" you are assuming that the photographer did not change or learn new information between last year and now, which is not warranted IMO.
No, I am
not assuming that - on the contrary, I specified that if the photographer gained
new insight into what, eg, "tonal subtlety" could mean her wants could change to match. I assumed only, as I think is reasonable in the context of this forum, that last year she thought about her photography and what could make it better. And my point was simply that, last year, thinking about what could make her photography better
must have included consideration of a medium format camera with the same 44 x 33mm sensor the X1D has. And if she decided last year that such a camera would not make her photography better she has no reason to think otherwise this year. How can this possibly be controversial?
Sure, maybe last year the photographs she was taking were not ones that would benefit from (say) more dynamic range, and the photographs she is taking this year are. I am struggling to think how that could arise in practice, but let's suppose it did. In that case, however - and this is the key point - she will be able to show us actual pictures she has taken that would benefit from more dynamic range, not merely refer to pictures she imagines taking that she imagines would benefit from more dynamic range.
Of course, maybe last year she did
not think about what could make her photography better, and did not want a larger format merely because she had never thought about it. But she did have
reason to want a larger format last year and if she had thought about it last year she would have reached the same conclusion as now. The same is true of a photographer who last year did not know what dynamic range is, and so did not appreciate that her photographs would benefit from more of it. But in this case also she had
reason to want a larger format last year, and if she had known then what dynamic range is she would have reached the same conclusion as now.