Sliding at First Base

I hear so many announcers criticize players for the head first slide at 1st base while running out a grounder. They very confidently state sliding slows the player down. What bothers me is you usually hear something like this to support their argument: "You never see a sprinter dive across the finish line." Sliding at 1st may or may not be slower but the sprinter comparison is illogical. Sprinters are racing across an imaginary finish line that stretches up to top of the runners. Baseball players do not have this imaginary line. Their target is a fixed base on the ground. A sprinter finishes when any part of his body crosses the line. If they changed the rules of sprinting so that to finish the racer must touch a base, maybe we would see more sprinters diving. Now that would spice up the sport.