Flying to many (small) destinations should increase CI because
a) It's realistic, isn't it?
b) Currently flying to many small destinations increase marketing costs beyond reason making high CI impossible to attain for an airline serving many small airports (in addition to big ones).
+5000 this will definitely help my regional airline, a lot.
While I agree there's a problem with regionals attempting to get high CI figures, I don't think this is the best way to go about it.
Sure, an airline that flies to many destinations, is likely to have a higher CI than one that flies to only a few. But that's because they market in a lot of places, not simply because they fly to them. So trying to make this a means to avoid marketing oneself is sort of missing the point.
This method would also benefit the mega-airlines that already generate unreasonable profits at least as much as any small regional airlines. And they don't need any help at reducing the costs.
It's a far better solution to simply have Marketing costs scale by the total demand of the route or perhaps using the Airport Size figures on each end of the route as a modifier. This would scale marketing costs realistically as it shouldn't cost as much to advertise one's service in New York City as it does is Des Moines.