From its beginning Star Trek dove right into stories about illusions. "The Man Trap," "The Menagerie" (or "The Cage"), "Shore Leave," "Errand Of Mercy," even "Mudd's Women" - things were not as they seemed and that was often bad. The danger of malicious misperception was real, grounded in human gullibility, and this was portrayed down to "Turnabout Intruder" again employing "things not as they seem" as a plot device.

"Your race would learn our power of illusion and destroy itself." Is any better reason ever offered than that provided by the Keeper? Right or wrong, somebody obviously believed it since visiting Talos IV gets you fried, the only mandatory death sentence left on Starfleet's books. (Even mutiny apparently doesn't make the grade, though Lester/Kirk was set to enforce the apparently optional death sentence before the chance was lost.)

Comparatively "Enterprise" has just dipped its toe. We've seen incredible holograms, several styles of shape-shifters, and a telepathic slug that can reach deep in the mind finding pleasant people to conjure as a representation. Likely any malicious misperception is coming from either the Vulcans (yes yes, they're really Romulans) or something in the Temporal Cold Bath. Daniels may have shifty eyes but that's probably as bad as it gets.

Speaking of those holograms, they came to bear much of the illusion-based dramatic weight. But a lesson percolated, one more optimistic than before. Using the holodeck isn't bad so much as using the holodeck against an unwilling other is. Perhaps the actual issue is rather of proper distribution of power, disabling any sufficiently motivated individual from mischief.

Otherwise, are we really that frail with respect to our own potential? Does a "monster from the id" await every technologically advancing species, a test behaving as a challenge? Recall Gary Mitchell, glowing eyes and all. Not quite an illusionist, but the point was the same - giving one individual the unstoppable power to create or deceive is a bad thing, up there on the scale with obliterating mining colonies (a la the Great Warrior).

Though the Keepers mention that Pike's refusal (to settle as work-slaves) condemns them, there's always the chance that humankind wasn't intended specifically. Given the war-brought destruction wrought on the Talosian survivors themselves, maybe they've falsely come to project the power of illusion as dangerous to any race that would wield it. So I like to think that, at the end of the story, Captain Pike returns to Talos IV to influence his huge-headed hosts with a life sentence. As in, live a little!