How about with the national coverage, more people become fans of teams and not of the game.
If you aren't watching this AMAZING world series, you should not consider yourself a baseball fan.
In 2007, the Red Sox won and it was a frightfully boring world series.
Now, some Red Sox fans may have loved it because their team won, but seriously, was there ever ANY doubt that they were going to win.
If you know a team is going to win, why not just save yourself 3 hours and get the highlights.
Lastly, Ratings cost you money.
ESPN pays baseball, advertisers pay ESPN and they get their money back through increaes in prices for the stuff you buy.
It's better for the fans if the ratings are low.
edit to asker: Did you bother to actually watch any of the first 3 games??