I think it's the fact I would need to connect to another train in Philly. That..... and the time/money hasn't really worked out for me to make a trip to NYC or points beyond. When I've had to go to philly for work, it's been easier to just drive due to it only being about 90min away (and the location i've needed to go to is in the outer metro area)....
and the only trip i've made to NYC since I've been in this part of the country was actually to drive someone I knew from the local school back home for the weekend.
Just goes to show how much I get out of this area going north. Most of my trips have either ended up being in the Baltimore/DC area..... or down there to catch a flight back home to Atlanta or to WDW.