
I remember a Dilbert cartoon about that - an engineer has a great idea, which his boss discards on the basis that 'if nobody else does that, it can't be any good'. A design that requires laser cutting (not a mass-market technique), 7001 poles (I think) - again, not a standard pole material, and the users have to seam-seal it themselves, may not appeal to the mass-market crowd.
Also, the design has some limitations:
1) The material used (parachute cloth) doesn't many US fire regs (an absolute no-no for mass manufacture).
2) The overall design relies on users being 'sensible'. Jack Stephenson alledgedly used to interview prospective customers to ensure they knew what they were getting. If you abuse the tent, in particular not following his (very simple but quite rigid) instructions for putting it up, then you risk damaging it. It takes <2mins to put up even in a storm, so I don't find this a problem.
3) The poles need looked after - they're extremely thin-walled, but much larger diameter, so once up they're very strong, but if you apply a point load they can be broken. I suspect a mass manufacturer would be faced with a lot of returns for broken poles from mis-use (already a problem for some tent manufacturers with existing thick-walled poles).
4) There's no warranty. You have (I think) 28 days to check it for problems and return it, and thereafter they will repair it for you (at $50/hr) or tell you how to do it. When a fox attacked mine and tore a bit, they sent me the repair materials for free and talked me through the repair on the phone. Frankly, for me a warranty is useless as I'm rarely in a location where I could take advantage of it.
That said, mine has stood up to 70mph+ winds (nr Mt Cook, NZ), torrential rain, 40C+ heat (oz outback) and c.150 nights continual usage on the PCT including blizzards and c.20nights in the snow. They've also been used on Denali and assorted other high altitude peaks. For a 1.3kg tent, there's nothing close to it. My next tent will undoubtedly be another Stephenson.