This is because the format changed. They used to geographically divide the country into regions and choose/establish the best teams from each region. So there was always a northeast representative guaranteed in the CWS each year.
When they changed to the modern format the regionals now have no tie to actual regions like they used to. You can now have every team in the CWS from the southeast if it works out that way. This never used to be possible in the old format and it is now much harder for northeast teams to qualify.
Maybe basketball should be more regional...hadn't really thought about that...
This year, UNC, Clemson, Alabama, Mississippi State, Charleston, and Howard were assigned to the West and played in Los Angeles.
Vermont, Wisconsin, Boise, Marquette, Kentucky, Duke, JMU were assigned to the South but out in Dallas.
Baseball and basketball, I reckon, have tried to be more "open" to the best prevailing regardless of location...