A few things:
Yes, a 15 year ABD is a sign of serious trouble. I clearly didn't mean to stay ABD forever. But it's not a bad idea to go on the market the first time as an ABD (assuming you really believe you can defend within a few months), then holding off on the defense if you don't get an offer. The following year, you can go on the market with the degree "in hand" and see if that makes a difference. If you really were close to finishing, then you should have at least one publication from your dissertation (or related work) ready by the time you go on the market the second time.
Yes, I suppose any job is better than no job. But ... since you clearly didn't get the job, why not at least chalk it up to a dysfunctional department. But, in all seriousness, if the department can't respond to you after you got an interview -- and you let them know that you have another offer -- there is something seriously wrong with that department.
The bottom line is that by now (early January), any one on the market should seriously start making the rounds in non-academic job applications (government, NGO, intelligence, analyst, etc). There's a vast world out there beyond academia that will hire PhDs in social sciences. Stressing out about the academic job market without a plan B is not constructive.
I can also appreciate flyoverprof's comments. But -- and, again, focusing on people who got on campus interviews -- there is something wrong if those who did get flown out weren't contacted. Here's my explanation based on my experience on search committees: When we bring in 3-4 candidates for job talks, we are as much trying to court them as they are trying to convince us to hire them. Even after we make our decision, we hope the other 2-3 candidate will leave with a positive image of our department. It's part of the long term strategy of networking and building a reputation. We realize that there's a good chance that anyone we bring in to interview may likely end up elsewhere (either because we passed on them, or they turned us down). We hope they take their impression of us to their future colleagues.
My sense from departments that don't bother with these kinds of courtesies is that they don't really care about the academic world beyond their campus. That may be fine for a Harvard or Yale, but not for an unranked school. I take it as a sign that they have little interest in building a reputation or networking with other scholars over the long term. And blaming the oversight on a decentralized search process doesn't sway me. I could take that as a sign that the department (as a whole) isn't all that interested in their searches and that at least a few people in the department in particular don't take their service obligations seriously.
But to get back to the main point by the OP: If they didn't contact you, they don't want to hire you. Plain and simple. How you interpret that is up to you, I suppose.