I would love to see these large airports replaced with multiple smaller airports. A larger percentage of the population would have an airport nearby, and average travel times would be reduced significantly. It seems to me that planners are optimizing for everything except your personal experience when they design and advocate for mega-airports.
There is a challenge with replacing all large airports with smaller ones, when using a hub and spoke model. If you have smaller airports, you have fewer destinations, and fewer connecting flight options. NYC (DC, LA, SFO, Boston) as a gateway to the US from overseas makes some sense - lots of O/D traffic, and for those that want to continue onward, they can. I fly from my local smaller airport, which I love. And whenever I can, I use my smaller regional airport. But it doesn't always reduce travel time - it often increases it due to the need to connect for most destinations. In fact, it'll be faster for me to drive to JFK (two+ hours) for an upcoming trip to eliminate a nearly three hour flight and one hour connection - in the "wrong" direction.