If it's over £800 people won't pay it. That's the point. Even The Quest 3's price was too high for VR adoption. The Quest 3s is outselling it.
1. It's Valve, they can do no wrong. This is true, but only for the tech community. Consider the Valve Index, a much better advancement in headset tech than the Steam Frame. You got a lot for your $999. A device that was definitely the best VR headset of the time. The original Quest was released at the same time. It sold more in the first 3 months than the Index did in it's entire lifetime.
2. It's not Meta. Again, this only applies to the tech community, the nerds etc. The ordinary joe does not care. It's not going to be something that's going to sway ordinary people if they are considering buying a headset. Price is still the single biggest consideration.
3. More access to Hardware? How many people will actually care about this? Even the techies? It's primarily a PCVR headset. Also, the hardware isn't as open as you think it is. (more in 4)
4. Not sure about any of this stuff. If it's really fully open, like the Steamdeck, then yeah, you will be able to put your own OS on it for whatever you want. There are tons of problems though. You will lost a lot of the VR Functionality. It's also an ARM based solution from Qualcomm, their SOC's don't use open source. And if it is like the Steam Deck, you want to put a custom os on it, Valve will say go for it, but you are on your own. One more problem with this headset with regard to work and training etc. Valve doesn't do that kind of thing. Whereas HTC, Meta etc. have a lot of experience in this area. They also have the support platforms in place.
5: Might not be as simple as that. see above.
6. Your points 3, 4 and 5 and this one are all basically saying the same thing. Besides you aren't locked into a single eco system with the Quest 3 either?
7. Why do you think faster development times or why does it matter? I doubt there will be any games made exclusively for the Steam Frame. It will just be like the Steam deck. You will have games verified to run on the Steam Frame with a rating of how well they will run.
Interesting phrase, the Potential of this device. Lets be real here. How many people who will buy the Steam Frame have any interest in making custom OS's, or whatever else? And yes, we have to focus on the spec as that's what we are paying for and you are comparing it to the specs of what has been out for nearly three years already.
Your example of a game is any entirely different situation. If told you the next Xbox was going to be only slightly more powerful than the current PS5 Pro but it would be open and you could run whatever OS you want on it or use it as PC if you wanted. But it was going to be £400 more. Would you be happy?
You feel like the minority? The Steam Frame seems to be aimed at the minority. It's too expensive for the regular Joe and offers very little if anything to the VR enthusiast. I bet if you asked, most people would sacrifice all the "open source" ability the headset has for Better lenses, displays and more powerful processor. Most would probably pay extra too.
Phew!! tired typing