I think there's a 4th option, although it plays into some of your others. I think it's open for purely cosmetic reasons--it's nice outside and it's Thursday night football. Fans love the game of football but the owners are still selling a product. If having it open sells the Cardinals for more prime time games I'm all for it.When the coach verifies that it does in fact matter...then we are only left with 3 options for the roof open crowd:
1) You feel looking out into the sky is more important than maximizing your home field advantage
2) You feel that since we have a stadium feature, using that feature is more important than maximizing your home field advantage.
3) You don't understand that sound reflects back and still somehow believe that it doesn't matter despite multiple people telling you it does.