ATC (Automatic Train Control) drives the train. Not the driver. With ATC, that person can walk inside the train, as a tour guide, first aid, cleaning (they won't like that), and security.
Interesting theory, but not true.
Here's why:
1) The driver/operator does work the doors. In order to do this from a single point on the train, it requires cameras that allow the operator to properly see the whole length of the train, these are present only in the cabs at the extreme ends of the train, not at intermediate points.
The doors do not operate themselves, and will not, until there are platform edge doors, which we do not have today, and will not, across all of Line 1 for many years.
2) The operator is required to be able to effect a slow-down or emergency stop due to someone being at track level or appearing suicidal. This is particularly important because the TTC has trains enter stations at speed. (I hear the comparison to Vancouver coming, and note that in Vancouver trains come into the station slowly (making them a less likely choice for an attempted suicide.), the TTC cannot adopt this practice without radically reducing Line 1 capacity.
Trains do not have track-level intrusion systems on board.
Platform Edge Doors would again resolve this issue.
So in 10-15 years, if we're lucky, your idea will work; for now, it cannot. The operators cannot leave the cab, at least for any meaningful period.