You just wrote it: the purpose of a demo is convincing as many people as possible to buy the full game, so the more the demo is captivating the best it servers the developer's interests.
And the camera turning around Jenna's hot body is captivating and may conquer a few more buyers...
I will buy the game on steam anyway. But just because I played the leaked beta.
In that, piracy has convinced me better than the demo
We're not saying "do a better demo or we won't buy the game".
All we are saying is that omitting that camera movement from the demo might be not exactly in the developer's best interest.
Just a suggestion