A common criticism of chumming to draw sharks for divers to see is that such observation is unnatural and it's 'more rewarding' to see them behaving naturally in unscripted scenarios.
Assuming they show up, and get close enough for a look and a photograph, maybe so. Many sharks would avoid humans without incentive to get close.
Another common argument in such threads is that if you don't see them now, you can see them later and it will be 'more rewarding.' Well, if you get in a lot of diving in the right spots that might be true. But a lot of people don't, and for them it may be 'now or never,' and they want to see a shark.
I get the impression the shark dive business draws a lot of patronage, so evidently it's rewarding for a lot of people.
I recently got to view nurse sharks and reef sharks 'naturally' diving off Key Largo, and that was fun. But given the chance, I'd probably do a shark feeding dive. I'd get closer, see more and could get closer photographs. It doesn't have to be an 'either/or' proposition; you can do both.
Richard.