There are many reasons for it to be as big as it is, that have been discussed extensively in this thread and others.

Is your constant ability to ignore and dismiss the valid reasons for downsizing the Denver pilot base some sort of defense mechanism?

also pretty ironic complaining about the reliability of BWI from a DEN guy. DEN is consistently a far less reliable hub than BWI when it comes to weather and ATC delays. Ground ops has issues both places but BWI has significantly improved over the last year or so.