The dealer I bought my 13 from sells half their JKs modded like this. They inflate the price a lot (no where near this extent) but that's how they end up haggling. To someone who doesn't know better, they offer to knock 4k off that price and they think they got a hell of a deal. Let's face it there are a lot of people with money out there that don't know better and just want it that way when they pick it up.
And nitrogen is my favorite. I will say in smaller tires it does help. The pure nitrogen does expand/contract less than straight air, yes the 20% other stuff matters. On my old track cars I ran nitrogen and the pressures changed a lot less on the track due to heat build up. But there's also not much "air" volume in them. Now on my JK with 35s it doesn't do crap. Discount tire refills mine every time I go in for rotation because they know I wheel it. I've told them several times not to but they said that is their policy, their customer service is awesome!!! Anyway, this winter it's been very cold in MI. When I go out in the morning and it's near 0 my pressures are reading 24ish PSI. On my 15 mile drive to work they get up to 29 where I run them. So much for nitrogen helping.