I think a large part of the reason for indoor concerts is weather. While the band is usually protected, it takes the crowd out of it if they have to battle the elements the entire time, and lets face it, most of their fans these days aren't going to sit out in the rain. Most outdoor concerts are general admission, so to get a good seat you sit or stand in the elements for hours, and most will not sit in the rain for crappy seats. Personally I'm glad nearly all the concerts were indoor, as I do not do outdoor concerts unless they are the type where they're cheap and I don't care if I miss it by staying at home if the weather is rainy or too hot (I skipped a MercyMe concert last August due to heat). Amphitheaters are OK as long as my seat is reserved and well under cover, but open seating like at a stadium? No way...

I'm sorry to hear our guys seem to think perfect acoustics without AC is more important than ensuring their fans don't roast in their own sweat at 85 and 90 degrees, which would easily be the temperatures higher up. I can appreciate wanting perfect sound, and perhaps venues who want to attract big name bands should start thinking about heating and cooling and sound when building the things. Maybe our guys should only tour in the winter.

ETA: If this really is true, can you imagine what the venue in Miami will be like in mid-July?