Could the island being using the freighter crew as replacements for those who may have died already?
Does the island need a anthropoligist, piolt, physicist, and a ghost buster?
I'm not sure about the island, but the story does need these people now. If they had been among Losties, we would have gotten too much science, overwhelming the mysterious nature of the island, too soon. Coming as they have now, we'll start to get more questions to gnaw on at first, and then someone 'qualified' to provide some answers. They'll continue to germinate more debate on the boards, too.
I hope they stick around awhile!