Every holo-character on the holodeck is the ship's computer. All of them, no exceptions, Moriarty, McNary, Leah, etc. They're just programs created by the computer based on requests and statement of the people (real people) who want to enjoy the holodeck.
The holo-character have no brains in their skulls.
Every time someone on a Starfleet ship went on and on about how they met this famous person or that famous person (nor not so famous), I just wanted to bang my head. "No Reg, you weren't just arguing physics with Einstein, you were arguing with the Ship's Computer."
Holograms cannot be smarter than the ship's computer. Where is the data or knowledge for a hologram stored? In the ship's computer. How did the ship's computer get all that knowledge? It was programmed or input by someone on the outside.
A computer is just a collection or the sum of it's knowledge.
They used every observable data point, every journal entry, every diary bit, every paper ever written by Leah Brahms to create her hologram. The computer gave some far-fetched nonsense about how 99.99% accurate (or whatever) it was to the real person, with a margin of error. Even IF, IF, IF that were true and capable of creating a hologram indistinguishable from the real person, that still cannot hold true for every historical figure. There is less data available, less diaries and journals for example, from Albert Einstein than Leah Brahms. Even less data to go on for Da Vinci. It's not possible to recreate these "ancient" personas and have them be anywhere near accurate.
Yet they all wanted to believe that Reg was arguing physics with Einstein.
Have to disagree with both you and T'Girl on this. Stipulated: yes, most
the computer. Einstein, Da Vinci, they were the computer. But the ones who do
go sentient, I venture, are not simply the computer suddenly becoming an AI (which it is not). They are emergent systems, comparable to a point with the magnascopic storm + computer = the nodes/new life form in TNG's "Emergence." The x-factors equivalent to the magnascopic storm in the case of the holodeck are programming by biological sentients in a very sophisticated materialization setup + direct physical interaction with sentients in 4 dimensions (probably the most important ingredient) + long/continuous running time. Not all of these are required, and the proportions that result in sentience are not always the same. For as long as these rare holosentients are being generated by the computer, they are more
than the computer--just as our minds require our brains, but are more than are brains.
Moriarty, Vic Fontaine, the Doctor--they're sentient, self-aware, and none of them think they're the computer.
I think in the case of the Dixon Hill setting that the writers were still playing with the idea, and allowed the characters self-awareness that they later decided should be much harder to come by.
So, my answer to the OP's question is: certainly not when we're dealing with 99.999999% of holodeck characters. In that remaining tiny percentage, moral issues absolutely do arise, and, for example, I don't think Picard's solution to Moriarty was moral at all, to trap this new being, who never was a crimelord, in a false universe for as long as that memory block exists. HoloMoriarty's crimes, as far as I know, included unlawful imprisonment of Starfleet personnel, and hijacking a starship. Not small beer, but not life-imprisonment-worthy by TNG standards either (or TOS standards; Harry Mudd committed approximately the same crimes, and had a reason to expect that some day he'd be getting off Mudd).