I once took a summer course on Transportation at Suffolk University (where I'm going for my Masters Degree in Public Administration) last summer. The course was taught by none other than our Mr. Mulhern. And he said the same thing about streetcars then that he's saying now. Then as now, he was convinced that streetcars are a thing of the past and said how "ridiculous" it would be to bring back the Arborway streetcar and how it would get stuck in traffic. When I told him about the Portland (OR) Streetcar and new streetcar lines in New Orleans and San Francisco in class, he told me that they are "boutique streetcar lines" (whatever that means). And he consistently raved about how successful the Silver Line was, acting like it was the greatest thing to happen to Boston since sliced bread.
I don't mean to sound like I'm bashing Mulhern, but everything you all have said in this thread has hit the nail square on the head, about his attitude on expanding rail service in Boston. It disgusts me that the T is considering BRT for the Urban Ring and Somerville. It will not be any faster than what is there, nor will it be as convenient - especially on the Urban Ring.
Meanwhile, check out
http://www.dctransitfuture.com . Our nation's capital is building light rail in the Anacostia section of Washington on a three-mile section of abandoned railroad ROW and will run it on a three-year trial basis. It will contain a transfer to the Washington Metro at its Anacostia stop. The fact that DC/WMATA is doing this, while the T and MA scorn rail in favor of Bus "Rapid" Transit within the urban core of Boston, Cambridge and Somerville - should really put the T and MA to shame. I really hope one day the T will wise up.