100% honest non sarcastic question: who is using FW800?
It's likely there because some video guys did invest heavily in it some years back. Wouldn't want to leave them out in the cold.
Can also think of it this way. They may add a couple ports that most don't need but the additional cost is minimal and given the choice between a 12 port or 13 port dock, most people are going to go with the one with more. Why not have the extra port there JUST IN CASE you need it at some point?