Empoleon is Steel/Water, which is a really strong typing, but it doesn't stick out as an OP starter. (Or do you mean a pure steel stage 1 starter? >.>)
I think LilJz1234 has the best theory about starter types. Each Pokemon guide I've bought since Gen 1 has come with a section about building teams depending on your starter. I think it's all about simplicity for new players.
But regardless, it would be nice to see some variety in secondary typing and ability. I'm still holding out for a part Dragon starter (Charizard?:'( ).