I don't know which Philly transit activists you've talked to, but the ones I know via Philadelphia2050 are completely meh about Market East. There was no local demand for it; the Penn Design people came up with it on the theory that HSR stations should always be put in the CBD, Amtrak seems to have adopted it, and now the proposal is $10 billion heavier for no real reason. 30th Street Station is where it is because the PRR found it better to have a station that could be used by through-trains from New York to Washington than to have all trains head into Broad Street/Suburban Station. Although not all decisions from that era are good ideas today, that decision is in line with recent practices from
Japan,
France, and
Spain, in which a near-CBD station with good transit connections to the CBD is good enough if it's too hard or too operationally constraining to enter the CBD.
Likewise, the Providence-area activists I know of didn't care much for HSR to Woonsocket. Of course based on city size the highest benefit comes from having a line from New Haven to Hartford cutting east to Providence and then to Boston, but the terrain is hilly and it's much cheaper to leave Hartford out and follow I-95. Until recently I'd thought that cutting Providence instead and following I-91/84/90 like in the Penn Design plan was a good second option, but the Penn Design plan has several tunnels whereas an I-95 route could be done without tunnels north of New Haven, and just two difficult bridges.
The importance of a working knowledge of best industry practices worldwide is that the rail discipline works by apprenticeship; too many insiders in the US today were taught by people who are used to FRA regulations, multi-conductor regional trains, separate concourses and ticket machines at each station for different kinds of trains, non-clockface schedules, long turnaround times, etc. This way, you have people who are convinced that the Providence Line is at capacity and the only way to program more intercity trains is to triple-track nearly the entire line.