This isn't a baseball thing, attendance is down across the board in live sports. I think the biggest difference in recent years is that nobody has the time to go to games anymore. Especially on weeknights. Then you add in the cold weather and 20-30 minutes additional time per game since the 80s. I went to one weeknight game last year and probably wouldn't do it again unless I had the following day off or something. And I don't even have kids. TV viewership is completely the opposite, I almost never watch baseball on weekends, only weeknights.