The Minstrel

2. There is no number 2.

OK, to be more precise, the other reasons are really contributing factors to the pace of the game:

2. Unlike most games, the team with the ball is on defence. It is in the defence's interest to slow down the pace of the game and throw off the timing of the hitter.
3. The action is broken up into discrete parts, where each side takes turns trying to score. Scoring can't suddenly occur out of the blue (solo home runs aside).
4. Since the season has so many games, the importance of each individual game is diminished, and they have less urgency.

So why do I love the game?

1. Baseball's slower pace means that you can enjoy watching an offensive sequence develop and unfold, similar to how a football fan can enjoy an offensive drive. (Football is a pretty slow sport too; it just has very intense moments breaking up a lot of standing around.) After, say, watching four rounds of the NHL playoffs, it's nice to be able to watch a sport where you don't have to be on the edge of your seat all of the time.
2. The number of games in a season makes the regular season a marathon in a way unlike the other major professional sports. As each individual game is less important, the cost-benefit ratio of a long-term injury is much higher, so players must take more care. Playing almost every day is wearing and players must pace themselves to cope with the grind.
3. Pitching -- The other major professional sports don't have the strategy and tactics of starting and relief pitching. A quarterback probably has more impact on a team than a starting pitcher, but there is generally not much strategy involved -- your number one quarterback starts if he is healthy.
4. Strategy in general -- The number of options a manager faces and how short-term benefits must be balanced against long-term ones are quite different in baseball than other sports. Nine field positions must be juggled while considering both offense and defence. Roster composition must be balanced, allowing for offensive and defensive substitutions (including pitching changes and days of rest).
5. Because baseball offense is composed of individual successes that for the most part don't require special teamwork, and since baseball is not a contact sport, the All-Star game can more closely resemble a real competition. (This isn't a very important reason; nonetheless, the baseball All-Star game is by far the most watchable of the major sports.)
6. Every game brings the hope of something new. The range of outcomes on each pitch is so rich, and the number of statistics that can be kept is so numerous that something fresh happens all the time in baseball, even after over a century of professional baseball history.

Baseball is a perfect summer sport -- usually a time when we'd rather sit back, sip a cool drink and take it easy. Its relaxed pace combined with complex strategy and neverending surprises make baseball one of my favourite sports.