My thoughts are right in line with what you've mentioned--there would be baggage that just doesn't justify the risk. I suppose that the fact that these coins are already on exchanges being traded would be a positive so these new dev teams could hit the ground running with raising funds with the spike in price and excitement. I haven't done the research but I don't think that these exchanges charge much to get their coin listed these day so this singular reason doesn't justify the headaches involved.