This is about as simple as it gets. There are two main kinds of shark dives. Baited and Unbaited.
If you want to see sharks in their natural environment, there are plenty of places you can go. These are unbaited dives. I saw plenty of sharks up and close and personal for instance on the wreck of the Spar off North Carolina. The ecological impact of this is minimal.
A baited dive attracts sharks to a location so that people can interact with them. There is an ecological impact of some extent that is hard to measure with a slide rule. Jim Abernathy's cageless endangerment dives for instance are in this category. With or without a cage, a baited dive is not for the ecologically sensitive diver.
Some of these baited dives are apologized for by people saying that "divers who already love sharks get a new found respect for sharks by diving with them" or some such nonsense.
A documentary filmmaker uses baiting to get the subject close, but every guy with an Ikelite camera seems to think they are Stan Waterman these days. The point being, running trips to a specific beach every week and baiting sharks to it is different than a one time film.
In short, if you claim to be all ecological, you shouldn't be taking part in dive trips where operators bait sharks thus altering their behaviors. The risk is not to you the diver. The risk is to the shark. For instance, somewhere off South Africa, poachers went to the baiting place for tiger sharks and poached them easily.
Leave.... only...... bubbles..... (if you aren't diving rebreather)
..Some academic advisor somewhere is about to get pummeled because you pointed that out 
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