People that don't like batters sliding into first base, because they think the batter doesn't get there faster. They do. Otherwise track runners wouldn't lean into the tape at the finish line. The reason for not sliding into first is all about injury. As an addition to this, announcers saying that if it was faster, track runners would dive at the finish line. The reason they don't dive at the finish line is because a rubber track to the face isn't so pleasant. Big difference between crossing a plane(finish line) and actually touching a stationary object on the floor. It takes less time to run two additional steps at full speed than it does to angle downward, propel yourself through the air, and then eventually touch the ground and slide to your destination. As mentioned already...in this scenario you almost have to decelerate to make the leap downward. But with me it's more about injury, and it's about the fact that it makes it harder for the first base ump to judge the play. A lot easier for the ump to listen for a ball hitting a mitt while watching a foot hit the bag, than it is to try and find a hand through a cloud of dust.