If you have just spent $1.5 billion on a new stadium, you should have the foresight to have it enclosed. Whether it be a retractable roof, or just a dome, that amount of money should take care of things like that. This goes for all teams getting new stadiums. The fans pay good money to go see games, and rainchecks are not practical for everyone. If you have do get off work early, or a take a day off, plus fly, drive, or take a train/bus/taxi to get to the game, you want to see a game.

The Yankees' front office has been complaining of the winds blowing routine fly balls into homeruns out in right field. If you think this is the problem, on especially windy days, you could close the roof (if you had one!).

I personally prefer the retractable roof to a dome, but either is better than nothing. With a retractable roof, you can leave it open and enjoy the fresh air and sunshine, and if the weather turns, it can be closed, and the game goes on. The temperature is also controlled, and you end up having better baseball, because the players aren't fighting the elements. This is the same reason the NFL went to having the Superbowl in domes and warm weather venues, better games=more fans=more revenue.