I wouldn't say "you certainly can't." I can certainly imagine someone being more willing to pay 2-class F prices for the seat (including pitch) in 3-class C than for the food in 2-class F. Perhaps particularly on flights like IAD-ORD where there's not really that much time for a meal anyway.

When it's my own money, I don't object in principle to paying for the food separate from the ticket. In fact, I've found that a lot of the BOB items (especially the fresh selections) were better than former free meals in Y and a pretty good deal at $5. At $9, of course, not so much-- that's probably enough to force me to buy something in the terminal and stuff it in my carry-on.

By the same token, I can't say that the hot meals in C have ever really impressed me. (Free booze has been a nice, though, along with the sundaes with real whipped cream.) I've had meals where I felt that I would've been better packing something myself or even buying something from the terminal. I wouldn't object in principle either to having the option of buying something of higher quality or not for a reasonable price. (The problem of course with a long flight is that eating really is required, so if you don't prepare, you would really be forced to buy.)

As regards the comparison between US and non-US carriers, remember that most of the changes here are domestic flights-- it's not that much better on non-US carriers on their own domestic flights. E.g., this FT post about someone surprised about how bad ANA domestic service is, and people telling him that that's typical. (Even on ANA's domestic but overwater routes where trains aren't a real competitor.) You might also note that they sometimes offer no food whatsoever on domestic flights in business class.

As always, of course, those flying on the company dime enjoying free upgrades (including when I do it) would not like having to separately report the food, alcohol, and sundae (if it existed, naturally) in their expense reports.