Playing everyone in the league once -- and radical realignment based on geography later -- is bad for travel, despite MLB claiming the opposite. And it's bad for TV times. It's also bad for attendance and bad for fairness.
TRAVEL
You're eliminating nearby road division games (2 of them), so you can play half the other league on the road too (farther distances).
You're also shrinking league series by a game to create more road series vs interleague opponents. Aka, you're playing MORE SERIES TOTAL, which is more flights; more time on airplanes.
TV TIMES.
You're going from 5 road series to the opposite division (W vs E, E vs W) to 7 one year, 8 the next.
The West teams are going from 12 road series vs the teams in East/Central divisions to 15.
Literally everyone in baseball gets more road games at 4 pm, 5 pm, 9 pm or 10 pm and less at 7 pm.
FAIRNESS
By reducing the number of four game series and playing more 3 and more 2 game series, you're increasing the chances someone misses an opponents' best starter. Huge difference between facing the Mets' Scherzer, deGrom and Bassitt vs the Mets Walker, Peterson and Williams.
Yes, everyone plays everyone now, which SOUNDS fairer, but it's now WHEN you play a team is going to matter a lot more. Baltimore, Seattle, Arizona... those teams were terrible in April, but are playing really good now. The Braves were mediocre the first two months and are playing .800 baseball now. While San Francisco, Milwaukee, LA Angles, NY Yankees... those teams were a lot better the first half of the season than the second.
ATTENDANCE
The reason that some interleague series draw really well is because those series are special events that happen once a year, or once every six years. You circle your calendar because if you don't go see Trout/Ohtani NOW, you've got to wait six years.
We can see this with Houston and Texas. Houston switched leagues. Here's average attendance for HOU vs TEX (both stadiums combined; removing COVID and Hurricane effected series) over 8-year spans
Both in AL: 31,293 (139 games from 2013-2019, plus 2022)
Interleague: 36,743 (48 games from 2005-2012)
And that's an in-state rival for bragging rights.
Everyone loves to point to the Trout/Ohtani or Crosby/Ovechkin effect. But for every team with an elite superstar, there's four teams without one. Sure, each team has good players, but Ohtani is a unicorn.
Not to mention that players change teams so much, you DON'T have guys who never visited somewhere. How many HOF guys played for just one team?
Baseball-reference HOF monitor leaders for players not yet eligible:
SEVEN of the top 10 hitters played in both leagues. The other three (Molina, Altuve and Trout) have played at least a road game at every MLB team. Molina's played in like 37 different stadiums; and Williamsport and San Juan.
EIGHT of the top 10 pitchers have played in both leagues. Other two, Kenley Jansen has pitched on the road vs everyone; and Kershaw has pitched on the road at 28 places. He's missed BAL, BOS; and his 4 starts at Texas were during the COVID neutral site World Series.
But sending the Dodgers to 15 AL cities every year doesn't guarantee he pitches at each stadium anyway; You've got a 40% chance of him not being scheduled to pitch!
Furthermore; the Trade Deadline. If it was so important to get everyone in every city... why do NO LEAGUES make sure that all interleague games are done BEFORE the trade deadline? Obviously, with 15 teams in each league, you need at least one interleague series happening at all times. But surely they could figure out a better rotation and then make the non-rival division series be early and the rival ones late?
Radically changing the schedule based on the argument that "Seattle fans deserve to get a visit from the Washington Nationals so they can see Juan Soto more than once every six years" only works if Juan Soto is guaranteed to show up. But that series was Aug 23 & 24 and he got traded to San Diego August 2.