Well, I don´t know if this is historically accurate, but its annoying and is killing the gameplay and fun playing with such units.

CA always tried to make RTW more playable, but this "feature" is really a bug in the way that it kills the advantage of such units.
Theire advantage is in the front and when they are drivting to the right, the left side is unprotected. And always to have another infantry unit there is odd.