So the demo was needed to participate in the SteamVR fest. It also adds some visibility from the free demo hub. But while many people have downloaded the demo, most have never played it.
It does not require a lot of work to keep the demo and playtest versions in sync, but still it takes a little.
I think people expect a DEMO to be a small part of a completed game, and they use it when they are just not sure if the game is worth the money. Even with the default 2 hour refund periode, its safer to just play the demo and then decide to buy the game.
The demo does have the benefit of only needing 1 click, and not the two clicks that the playtest needs. But the game is currently more in a playtest-y state.
VR games look very different while in VR, compared to the trailer graphics. So I will reactivate the DEMO in the future when it can serve a purpose again.
Thanks for everyone who did play the demo.