I go from DC to Boston weekly and couldn't disagree more. The NE Regional or Acela add, all things considered, anywhere from a 4x - 8x time multiplier over air travel, and is about double the cost on average.
Even when I was going DC > NYC years back it was barely worth the trouble, and still more than flying, only benefit being you land right in the middle of NYC and don't have the nightmare transit from NYC area airports.