And I'd argue that those who cling to the AL/NL names like they really mean anything at this point are the ones living in a time warp. Again, at this point, the AL and NL are just names and aside from the DH rule, they're little more than conferences.
...(keen observations)...
Where are the legions of Brewers fans and Astros fans who've permanently given up on MLB now that their teams are in the other League? I'd say right now that, aside from complicating my fandom with the Tampa Bay Rays, I'd have no problem with the Pirates being moved to the AL.
You're not WRONG with any of that. But I disagree on the overall mood of baseball fans, and the very sane, smart reason to retain the NL/AL split.
Yes, baseball fans gripe when you miss with tradition... then they get over it. DH, expansion, Interleague, Milwaukee, Houston. It's WRONG at first, then still a little weird after five years, and after 10 you get used to it, and after 20 it's the comfortable normal and don't change what it IS NOW. So if they destroy AL/NL, people will complain and act like grumpy old men yelling at kids to get off their lawn... and in 20 years, it'll be fine and normal.
But that isn't the point. The two points are:
#1 - Baseball has always sold "history" and "Tradition" and "The National Pastime" as part of it's appeal.
Fans - in all sports - are nostalgic for the time they think the sport was the best. Usually your formative years. My generation wants the Expos back in baseball, just like we wanted the Winnipeg Jets back; and still want the Nordiques and Whalers, Adams, Patrick, Norris and Smythe back.
Attendance data for the NHL shows fans less interested when the visiting team is a newer market (TB, OTT, FLA, ANA, DAL, COL, CAR, NASH, CBJ, and the Minnesota Wild). Winnipeg's road attendance was a big bump around the league when they came back. The same thing didn't happen with the Wild. Because Winnipeg was the JETS AGAIN, and "Minnesota Wild" didn't restore nostalgia.
In baseball, the same thing is true. The newest eight teams don't really move the needle like the historical ones you grew up with.
I'm a Mets fan, we had a good rivalry with the Braves since they joined the division because we were both good from 1996 to 2002 and having huge battles. But I wish we played the Cardinals, Cubs and Pirates more, because I remember THOSE rivalry battles from when 2 or 3 of those four were all good from 1984-1992.
#2 - and FAR MORE IMPORTANT: 30 to 32 team leagues are simply too big to "Play everyone in the league, since it's one league" while also playing the traditional rivals you had back when the league was 16 to 24 teams.
The NHL loves those Rivalry Night matchups: MON-TOR, NYR-NYI, CHI-STL, DET-CHI, PHI-PIT, TOR-BUF, BOS-MON, WAS-PIT, ANA-LA, SJ-LA. But playing everyone in the league home & away has slashed those games from 8 to 6 to 5 since the 1980s.
So combine those two items:
Most MLB teams have been playing the same 11 or 12 teams in their league between 9 and 18 times for the last 50 years. It started at 148 to 162 games against the same teams.
They lost MIL, added interleague, added TB, added Houston. So this season, those AL teams are playing their traditional 12 opponents between 116 and 128 times. Then it started dropping to make room for adding TB, ARZ, COL, MIA, swapping MIL and HOU, and adding 20 interleague games against teams you never played before.
Now you're going to play 6 games each vs EVERYONE IN BASEBALL after radically realigning.
Baseball isn't like NHL or NBA. It's actually harder to allocate games to the teams you feel you should be playing compared to NHL/NBA. Even through they have almost DOUBLE the games and NHL/NBA, they play 52 SERIES. So you're trying to allocate 52 series among 31 other teams.
It's extremely difficult to manage "playing everyone" vs "maintaining rivalries" and this new alignment -- which seemingly creating "regional rivalries" (which few actually care about), it eliminates baseball's built in excuse to SCHEDULE like you could when you had a 20-team league.
Let's be honest, fans mostly want to see about 20 teams max and don't really care that much about the other 10. The problem is that in MLB and NHL, everyone's group of 20 is mostly the same group of 20. So you give teams 16 of the 20, force 4 on them, and everyone gets most of what they want.
Or you water down the schedule by forcing ALL the unwanted opponents on each team each season.
Everyone who claims they like seeing every team in the league will always point to things like "I want to see Crosby, Ovechin, Montreal, Toronto, Detroit visit us in Vancouver each year!" while ignoring that they really don't give much of a crap about FLA, TB, CAR, CBJ, OTT, BUF, NJD, or NYI.
Most fans don't have full season tickets to 41 NHL or 81 MLB games. Why do they need every team in the league visiting once a year? It's 2017, you can get the entire MLB or NHL regular seasons in HD for $160. I've got both MLBTV/NHLTV and it's more hours of regular season games than there are total hours in a year. And that's not counting the playoffs.
Playing everyone at least once home/away is a really stupid thing to try to do in a league that big. And MLB has an excuse to avoid it, and they want to do away with it?