daniel_saunders (above) in his recent analysis of the early JNT era made an interesting point that the 80s tended to re-imagine monsters not as they were, but as the public remembered them to be. I think something similar is happening here, especially as most of the public probably did little more than recall what the Sontarans looked like. Although I'm also pretty sure Davies wanted a comedy monster and repurposed them to fit and I think the concept has been pushed a bit far. Strax is easily the weakest aspect of the Paternoster gang.