Actually, I have to disagree. I don't find the Amfleets to be particularly claustrophobic. The seating space is as roomy as the heritage cars they replaced, and I've had no problems with the capacity of the overhead luggage racks. For one thing, they're open racks, not bins, so I can easily fit a pair of 210 cm cross country skis up there. There's plenty enough room for any kind of suitcase that someone can reasonably carry aboard, there's a railing that keeps luggage from sliding off the rack, and it seems to me that the racks are a bit lower and are easier to hoist stuff on to, as opposed to old fashioned open luggage racks of the type that you can still find on the old single-level MARC cars. I also like the indirect lighting, which makes the interior much more restful and calming than, say, the Acelas, whose bright overhead lights and white walls has all the ambiance of those old single-level MARC commuter cars.
That said, the Amfleet windows are definitely too small, and the setup on the Am-1s, where one row of seats in the middle has absolutely no window, would be a bit claustrophobic for those forced to sit in that row.
However, given that these cars were put into service in 1975 and are still running strong is pretty amazing. I hope that when they're retired, a lot of them end up in museums and on heritage railways so that future generations can see what we rode on for close to 50 years.