"Tell me something, Dixon. When you've gone.... will this world still exist?.. Will my wife and kids still be waiting for me at home?" - McNary from "The Big Goodbye"

What that episode, which I believe introduced the holodeck, set up was both sides of that device. On the on hand, it's fun and adventure (minus the occasional glitch). On the other hand, it creates a serious moral crisis not dealt with enough which is captured in that quote. You're creating beings, denying them the chance to be anything, and then -with their ignorance- erasing their existence when the fun is over. And the easy thing to say is that they don't really have emotions and are just facsimiles, but we've seen that is not the case time and time again, from Moriarty to the Doctor. Even if you argue they only gain sentience later, there is still the moral dilemma that you are denying a being who would gain sentience the right and ability to do so. You could argue the same things they argued for Data's sentience and definition of being a being.

And as we saw with "The Big Goodbye", the only solution hinted at is just not to inform anyone they're holograms created for amusement. That doesn't solve any of the moral dilemmas; it just sweeps it under the rug and creates a blissful ignorance on both sides.

Thoughts?