I would echo Crash's second paragraph and add that there wouldn't be Major League Baseball in Houston today without the Astrodome. Outdoor conditions were too inhospitable to attract large crowds in the summer time (as anyone who took in a Sunday afternoon game at Colt Stadium in Summer 1962 could attest). Even at that, Houston had to fight off attempted moves of the ballclub to Washington D.C. and Virginia during the low-times of the late 70s. They weren't on really solid ground under McMullen either. Houston doesn't love baseball the way it loves football and it would have been difficult to make it work economically were it not for the air-conditioned confines of the Astrodome.

While we're comparing the Dome with MMPUS, let's not forget aging and the lack of upkeep the Dome has experienced. Let's see how good MMPUS looks/feels/smells in 2034 and then compare it to the way the Dome was in 1999.