Why is the placement of the series resistor in data lines important?
The purpose of a resistor placed here is not to limit (or limitate) the current, nor to increase the rise and fall time of the signal (though that's what it would do if it were feeding a lumped capacitor).

The purpose is to match the source end of the transmission line formed by the track. This means that when the unterminated far end of the line reflects the signal, those reflections will be absorbed in the source resistor, resulting in a clean signal received at the far end. Without that resistor, there could be multiple transitions at the far end, distorting the signal.