Those who are against criticisms of Virgin Galactic - you know I'm looking at you, JTFS, but you have a lot of friends out there - seem to have accepted some vague claims by Branson that his project is not just about making the world's longest rollercoaster ride, but involves doing research which will be generally helpful to humanity and transport in the future.
Now, while I accept that rich men are free to spend their money on vanity projects if they want, I detect a distinct lack of skepticism about Branson's claims.
Here, in this 2011 interview, he says that he hopes it will lead to very cheap small satellite launches, and superfast intercontinental airline travel.
Yet, as I've learnt from Googling after this crash, the height the SpaceShipTwo could reach has been downgraded somewhat because of engine issues (and the weight, I think, of carrying additional passengers compared to Rutan's SpaceShipOne.) I know there was a new engine being tested, but it seems very unclear if it will get to the old, advertised height, too.
It might be that an unmanned future version of the SpaceshipTwo may truly be able to launch small satelittes into orbit, but has anyone looked at its likely cost compared to more regular rockets? In fact, we already have an air launched small satellite system, and if you wanted to build an alternative one, surely you can get to that end a lot faster than via mucking around with designing a spaceplane for passengers.
And as for superfast intercontinental flight - as far as I'm aware, no one has ever seriously considered that rocket engines would be practical for that. Scramjets, yes. Does Branson's project have any relevance at all to scramjet research? I doubt it.
Being skeptical of Branson seems well worth the effort...