[Lucid:]

I think the secondary types would be interesting only because it would give the starters that are weak to each other a secondary type advantage over the other. Fire weak to water? No problem! Psychic is strong against Fighting! It would be a cool dynamic to the typical rock-paper-scissors starters. However, I am not opposed to pure typings all the way through the evolutionary line. They haven't done that since Gen 2 and pure types aren't necessarily weak.