Batter-Runner and possible 1st Baseman Obstruction?

[mkntrds]

Ok, to be clear then:

A first baseman can run through the white bag into the batter-runner, even though the runner stays in the basepath with the intent to run through the orange base.

This seems dangerous for the batter-runner. Any large 1st baseman would have an advantage over small/fast baserunners. Why then would any large 1st baseman not do this every time a small/fast leadoff batter hits a ground ball to him.

I see how this is avoided with second, third, and home plays - the runner usually slides. But with the batter-runner running through the bag at first, hard collisions seem unavoidable. Should the batter-runner slide? Am I missing something important?

(I'm trying my best to explain the situation.)