It would be very convenient, to select multiple countries for one shipping rate. Currently if I want to separate the countries for which USPS offers tracking from the ones which don't, I'd have to create a shipping rate for each (about a dozen or so).
This feature would also make it easier to maintain a rate for the list of countries that need extra attention. Again, currently you'd have to create a separate shipping rate for each individual country.
Even if these countries have the same shipping cost, I'd create separate shipping rates with additional information in the description (tracking, expected delays, etc.).