I agree with your point about Crawford; the game did such a great job at establishing how twisted they and their leader, Oberson were. I was really pumped for a great stealth and seige sequence, but then you learned they were all slaughtered and you face more zombies again. It seemed like a missed opportunity.
However, I think that there might be reason for that in that Chapter 5 might explore it more and the humans that were there. Even if Crawford fell, I doubt every single resident was slaughtered; there have always been some survivors to every given location so far and I doubt Crawford is any different. I think that Chapter 5 will show more connections to that place and face challenges that were hinted at in this chapter. Perhaps several survivors are trying to retake the town again and this voice figure has some agenda for it.
There are so many possibilities, but I think we might see something similar to "the Crawford siege" that was hinted at in this chapter appear in the next. Lee and whoever goes with them are right underneath that location and it seems like thousands of walkers are heading there as well as if someone is leading them there for a purpose.