The short platforms through out the NEC has been a point of contention for many posters. NYP definitely has some, Wilmington, Baltimore, & even WASH after PRR shortened all the upper platforms by 2 car lengths.
Penn south at NY will have longer platforms but that does not take in present tracks 1 - 4. In our opinion getting longer platforms at stations should be a number 1 priority. Unfortunately that is not as sexy as new trains, higher speeds, stations, CAT, and so on.
Longer trains with platforms that can just have one stop for loading can dramatically improve a line's capacity. If NYPS and all the out lying stations could handle 14 - 16 car trains line capacity would improve markedly. Of course longer trains would mean 1 o2 trains per hour less as standard interval from the end of one train to next train has to be maintained. As well it would take slightly longer to clear the ladder track inbound or outbound. That is one reason Amtrak needs to rebuild "A" interlocking so trains can travel thru the interlocking faster. The temporary speed reductions at NYPS really gummed up the schedules. ( Temp 10 MPH now back to 15 and maybe 20 once work is complete ? )
Unfortunately there are some agencies that have not planned for future longer platforms. VRE is a prime example of that problem as some of their stations already have too short platforms for their sometimes longer trains. Right now VRE cannot operate more trains so once their new daytime layover facility is finished they are going to have major problems with longer trains but not longer platforms.