In a perfect world you might be right. But with timezones, rl responsibilities it just isnt practical, specially on servers with tons of areas. And with the desire to move people about instead of everyone on the same map, this could really help. The suggestion dosnt say exactly where a person is specificly, it just lists maps and how many players are there.
As to the tell for help. Even without this system such is/was possible.
So far the pro's seem,
* Can tell if a Dungeon is already being done
* Can find RP more Easily
* Can tell which areas see the most frequent use
Suggested Con's,
* Can tell if there is a spy about (Solution: Use a private inn room or similar area with a lockable door)
* Can/Will be exploited (Solution: Since no specifics are given you cant really exploit where anyone is. You can only see how many people are where)
Any others?