I am firmly of the opinion that drawings from life (even poor ones) have more artistic liveliness than drawings from photographs. The process of transposing three dimensions into two gives the work an energy that cannot arise from simply copying shapes from paper.
Over time, drawings from life continue to live on and remain in many ways vibrant, regardless of whether or not they resemble the model. And often an expressive resemblance to the model remains even when details are inaccurate — this can be seen most clearly after the passage of time, when the drawing can no longer compared to the real thing in front of it.