I don’t think it’s only Brooklyn per se (although out of town would probably be more open) but I don’t live in Brooklyn and the community I live in is very nice, warm and all. But we are giving a BT a hebrew name and her mother and grandfather want to come. We were discussing which shul to do it at, and immediately ruled out the one we daven at because it is a FFB crowd and they wouldn’t feel comfortable because no one would say hi or go up to them and make them feel welcome.
It’s a mentality. It probably started when they were young, as a protection – don’t hang around people not like you because they might be bad influences. It’s not right, and something should be done about it ASAP because it’s a tremendous chilull Hashem (which for the record is a greater aveira amongst Jews than non-Jews…)