The Metro recieved more design attention that probably any other US system when it comes to asthetics, architecture, operations, etc. It was designed to fit the "monumental" status of a major world capital. I think, in large respects, they succeeded.
To quickly answer some of the other points:
1. I don't know that the cars are much wider than some others (Boston's Red Line for example uses pretty large cars), but, the width allows for more seats without sacrificing room for people to stand and circulate. The Metro uses mostly cushioned 2+2 seating...virtually unheard of for subway cars. This is a Metro advantage...they could accomodate the wider cars fromt eh start since they weren't having to fit into 100 year old tunnels.
2. Answered by Walt, it was all part of the unified design. One descision made early was not to have a hodgpodge of designs, but one unified style on the entire system. Newer stations are straying a bit, but not far.
3. The lights on the platforms are there as a safety measure. The system was designed before the "tactile edge" became standard in the 1990s. (Note that this edge does not have to be yellow...Chicago's CTA uses blue.) Even though I've been on the Metro within the last few months, I can't recall how they're working it into stations...perhaps someone who looked down the last time they were in a station can fill us in.
4. The Metro was always heavily policed/secured, even before 9/11. Passenger safety was a focus from the start. I can recall as a kid in the late 80's (when I logged a lot of Metro miles with my family) that you were hard pressed to not see police on the trains on a ride of any meanigful distance. They've also always been very serious about the no food/drink rule...the sacrifices one makes to get padded seats and carpeting in your subway cars!
There is a very good, though probably now 15 years old, book called "The Story of Metro." I recommend it to anyone who wants to know more about how the system was concieved, designed, and built. Well worth the read for any Metro fan or even just general transit fan.
Wondering if I'll see the Western Route double-tracking finished before I retire...
Photo: Melbourne W7 No. 1019 on Route 78, Bridge & Church Streets, Richmond, Victoria. 10/21/2010