Hell, why not have both!?
Yes, the west tunnel is ONLY for the airport. To reach the park one would have to cross the runways so THAT is not going to happen. It is also not a great route for crowds as there are elevators on the land side and escalators on the airport side.Yeah it'd be really awesome to have a bridge on the east end as well, especially since it's pedestrian and cyclists only. I'm not sure how practical it'll be considering there's quite a lot of ship traffic through that area though.
I haven't used the west end tunnel for a long time, but I recall the other end is basically the airport, and you can't actually walk "out' to the island proper?
Has anyone ever considered just getting better and more ferries? I know the city hasn't but maybe some enterprising random architect?