to a pair of old stadiums - say RFK Memorial or the Astrodome in the US, or maybe Azteca or Old Trafford abroad.

Newer is almost always going to be nicer. Especially where there is massive funding available. I don't know if that makes it a sad comparison. Rather it's just what one should naturally expect. Until an old stadium gets to the point of a certain age or level of archaicness - think old Wembley in London - it doesn't financially make sense to tear it down and build a new one. But when it does, weather in the US or abroad a beautiful new edifice takes its place.

Same thing goes with airports. JFK and LAX have been around for decades, they are not lavish but are functional. Not every NFL team gets to play home games at a place like Sofi. Not every major municipality is going to have an airport like Singapore or Doha or the new airport in Dubai.