I have a good friend who is a JBLU captain -- asked him about this a few days ago and he just shook his head. Basically "s*** happens", what are you gonna do, can't control the weather, but yeah, we make it up eastbound. Still, an "unscheduled" stop raises hell with the pax, not to mention the schedules.
Personally, I have to wonder if the "bus" is the right airplane for these routes,even though I find it to be a more comfortable ride for the passengers. (Well, me at least). Checking "FlightAware" ther are currently five flights scheduled for an SLC stop today.
Reminds me of a flight many moons ago when Western Airlines was operating JFK-SLC flights. They had three a day at the time, two were DC-10's but the mid-day trip was a 737-300. Naturally the 737 was the one I was on. The captain said there would be strong headwinds and that he was planning five hours fifty minutes en-route. We took off. Six hours ten minutes later we landed in Casper, Wyoming for fuel. Still another hour plus to go!
The monotony was reduced however, by the fact that I was in first class and seated next to the actress Glenn Close. She was on her way to Jackson Hole. We spent the hours engaged in splendid conversation.