On Wikipedia, it is stated that the Biot-Savart law is a formula used for determining the magnetic field pseudovector B(r) at a position vector r due to a current-carrying wire, but that the formula only works for constant/steady electric currents. Wikipedia then states the law:
So my question then is, if the magnetostatic assumption is employed, would it be okay to factor that current term $I$ out of the line integral? And if it is legitimate, why do most textbooks leave it in the integrand? Is there some hidden benefit to doing so?