From the limited knowledge that I have of that AD, I think it's not only the aircraft characteristics that limit it. The fact that it is right in the middle of a densley populated area might have something to do with it (NIMBY's and noise levels, saftey considerations etc).
Of course, the steep approach factor that you mentioned is also important as they will only allow a/c cleared for approch path angles of 5.5 deg or greater. Which rules out most shorthaul type jets that are best operated on a 3 deg basis (due SOPs or FM data).