Would've been really convenient for the City Hall bureaucrats! I admit that it is kind of romantic to have a "City Hall Station", but it makes no sense and it would've just bypassed two important subway stations! Honestly, what were they thinking?
Yes, but not everyone wants to walk such a long distance. Doesn't seem like a good argument, considering how many people commute to the Financial District and how important Union Station is as a transportation hub. The fact that this is of the most important employment hubs in the entire region means that we can't dismiss the convenience of hundreds of thousands of people. Some people like to walk, but many are commuting in from faraway suburbs and the last thing you want to do is make their journey even more tedious.
We can't just say, "it's okay, we'll build a City Hall station for the bureaucrats, but the rest of you people can just walk 10-15 minutes."