A hologram is just part of the larger computer. It would be like trying to say that my left arm was sentient. Anything my left arm does is because of me; I am sentient, not my left arm.
There's no reason why parts couldn't be capable of something the whole is. Say, your left arm is capable of lifting, but it doesn't follow that your left thumb would be incapable of lifting because it's "just part of the arm".
By your logic, Siri is sentient. If it doesn't matter if you're capable of unconsciously reprogramming your goals based on experience, then any sophisticated search algorithm should quality.
I'm not sure what Siri is, but "any sophisticated search algorithm" is a perfectly valid description of human sentience, or part of it anyway.
They do not have any programming equivalent of a 'Prefrontal cortex', so they are able to perform the complex tasks a human can but aren't able to form a real identity or real goals of their own.
We can't say they lack such a thing; we can at best argue they don't utilize such a thing. What good would it do for them to
omit the capacity? The holodeck is often required to out-think humans so that it can properly meet their complex, conflicting and not completely conscious demands. And we are not aware of any penalty in "programming costs" or whatnot that would countermand the utility.
Heck, for all we know, each doorway has a sentience routine installed so that they can open at the dramatically opportune moment! You don't optimize technology pennywise when you have the sort of wealth demonstrated in TNG; even today, engineers put highly capable processors into stupid keyboards because that's more convenient than designing less capable processors.
You can say "He's just faking it" till the cows come home about any and every aspect of holographic legerdemain witnessed in TNG, DS9 or VOY. But you can say that about any and every aspect of
human behavior in the shows, too. And you will of course be factually correct since they are just actors - but that's "out-universe", and so is the idea of judging the holographic programs by the programming standards of today and belittling them as the result. If they fake it so well that there is no difference to the outside, then there's no difference, period.
Vic can't even stop performing. He can't possibly want to, and he can't gain experiences that causes him not to want to.
Now where did you get all that? It's certainly not in the episodes. You're trying to prove a negative at best.
If you think there's no difference there you should feel like a murderer for eating vegetables.
I think you have it the wrong way around. I advocate a broad definition of sentience because I want to demonstrate the variety within. I have no problem murdering vegetables, but I have no problem murdering fellow humans, either - certain kinds thereof, that is. (Hell, I'm licensed to do that! They'll even give me medals for the murders if all goes well.) There's nothing categorical about such issues, despite certain popular illusions to the contrary.
Timo Saloniemi