Spanish is highly interesting to us, as the language spoken by so great a portion of the inhabitants of our Continents, with whom we shall possibly have great intercourse ere long; and is that also in which is written the greater part of the early history of America.
I think the reason behind why they first stated "Spanish is highly interesting to us" instead of just the reasons is because Spanish is only interesting to the U.S. since there are many Spanish-speaking inhabitants. Without them perhaps Spanish wouldn't even be interesting let alone a language which we would likely learn rather than others. Because it is useful in our own country many Americans are inclined to learn it but looking at other countries around the world it goes to show that Spanish in general is not that popular in other countries but rather English and Chinese. Spanish does, however, have a large base since almost the entire South America speaks it.