I don't know that they would want to advertise this benefit. Let's say you book a r/t and the o/w fare that you booked a week ago was $250. Well, if you want to change to a different flight the day of departure from DCA to BOS or visa versa, the fare is typically north of $399, o/w. The more people that take advantage of the benefit, one could say the more money B6 loses because last minute tickets couldn't be sold at that higher fare. B6 typically matches US' pricing on this route now, un-like in the past. In the past, I suspect they left a lot of $$$ on the table not matching their fares.

Yes, the change fees are But, IME, the pseudo 'shuttle' that B6 runs is always stressful. It seems like every flight is boarding late with no reason given, un-assigned seat pax rarely have tickets printed prior to boarding, and the gate agents are constantly running back and forth to the plane trying to assess how many seats are left. As sbm12 points out, policy is 30 minute cut-off, so why are agents running around like chickens with their heads cut off? Couple that with the non-enforcement of baggage policy and that makes for anxious experience. With US' shuttle, I never, well, very rarely, see this chaotic boarding process and the crews are much more proactive with advising the gate agents that by Group 3, over-head space is gone, so it's time to gate check. IME, US just has the shuttle service down, and the experience is far better. I hesitate to use the word 'polished', but US is definitely consistent and professional.

Non-stops ex-BOS is really what keeps us flying Jetblue as they do provide a nice in-flight service to leisure destinations. It's great to have non-stop service to say, MSY, FLL, CHS, etc. from BOS, but for me, those are typically vacations, not a shuttle service, so the inconsistencies can be forgiven. For a shuttle service, I want schedule and consistency, which JetBlue isn't great with. Even the flight times vary from week to week by about 30 minutes.