I think you could make the argument that the West Region hasn't had enough success to host a regional ever year. Maybe every other year. Look at the data from the past two decades. If they were carrying equal weight, their numbers would be right at 25%.
2000-2009
1 seeds:
Stanford (3)- 2000, 2001, 2004
Arizona (2)- 2000, 2003
Washington (1)- 2005
UCLA (1)- 2008
Total 1 seeds: 7/40, 17.50%
Final Four Teams:
UCLA (3)- 2006, 2007, 2008
Arizona (1)- 2001
Total FF Teams: 4/40, 10%
2010-2019
1 seeds:
Gonzaga (3)- 2013, 2017, 2019
Arizona (1)- 2014
Oregon (1)- 2016
Total 1 seeds: 5/40, 12.50%
Final Four Teams:
Gonzaga (1)- 2017
Oregon (1)- 2017
Total FF Teams: 2/40, 5%
Past 20 years combined:
1 seeds: 12/80, 15%
FF Teams: 6/80, 7.5%
And, of course, 0 for 20 on winning the national championship. Only Arizona (01), UCLA (06), and Gonzaga have even played in the title game.
2000-2009
1 seeds:
Stanford (3)- 2000, 2001, 2004
Arizona (2)- 2000, 2003
Washington (1)- 2005
UCLA (1)- 2008
Total 1 seeds: 7/40, 17.50%
Final Four Teams:
UCLA (3)- 2006, 2007, 2008
Arizona (1)- 2001
Total FF Teams: 4/40, 10%
2010-2019
1 seeds:
Gonzaga (3)- 2013, 2017, 2019
Arizona (1)- 2014
Oregon (1)- 2016
Total 1 seeds: 5/40, 12.50%
Final Four Teams:
Gonzaga (1)- 2017
Oregon (1)- 2017
Total FF Teams: 2/40, 5%
Past 20 years combined:
1 seeds: 12/80, 15%
FF Teams: 6/80, 7.5%
And, of course, 0 for 20 on winning the national championship. Only Arizona (01), UCLA (06), and Gonzaga have even played in the title game.