I used to commute from the Red line to the Blue line. In the mornings when I was in a hurry I would take the Green from Park to the now-closed Government Center

I used to commute from the Red line to the Blue line. In the mornings when I was in a hurry I would take the Green from Park to the now-closed Government Center and then pick up the Blue, but in the afternoons I would get out at State and walk to either Park or Downtown Crossing. As you say, it's only a few minutes' walk, and very pleasant to be in the heart of the city. Every so often in the morning the Green line was even delayed enough that it would have been faster to walk instead.