Because I believe in tradition. I believe in the sanctity of the National League. I believe in pitching inside when the batter crowds the place. I believe that defense matters. I believe in right fielders with cannon arms. And I oppose the designated hitter with every fiber of my being. The two leagues should never intermingle until the World Series.
The Astros were brought in as a NL team. I grew up following the old NL West with the Astros, Reds, Braves, Dodgers, Padres, and Giants. My Braves would finish 40 games out of first place, but Phil Niekro would lead the league in IP, Ks, CGs, and Shutouts. I remember giants like J R Richard and Joaquin Andujar bringing respectability to Houston, battling the hated Reds and Dodgers.
The National League should not be a home for the old Seattle Pilots. They are an AL spinoff, and should be returned pronto.
And besides, the American League is gay.