Actually I think in most cases that’s good. Touching the third rail is lethal, so when passengers just pull the emergency brakes and brake out, this will be a hazard. Even rescue personnel, won’t accesses these places without having the power switched off first.

When there is fire, you really don’t want to stop in the middle of a tunnel. It allows little accesses to those who want to flee and the rescue personnel to enter. Stopping at a station will allow passengers to exit the train much quicker and allows fire-fighters to put out the fire quicker and more easily. Although the advantages vary depending on the design of the stations. I’m not familiar with the trains in the US, but carriages should contain the fire long enough to stop at a appropriate location.

Same story for the medical problems, EMT can easily enter stations, but tracks are a totally different story. EMT’s will generally be quicker on the scene when the patient is at a station.