If you said you saw a ‘Canis lupus familiaris‘ in your backyard, nobody would know what you were talking about, but if you tell a ‘Dog’, then they would easily know. So why a scientific name is so difficult?
Carl Linnaeus (1707 – 1778), a brilliant scientist, established the modern scientific method of ‘binomial nomenclature’, or two names, in which the first word was used to describe the genus and the second, the distinguishing characteristic of a specific living thing, and sometimes the inclusion of the name of the person who discovered it.
At the time of his work, Latin was taught everywhere and was uniquely suitable for this system of naming plants and animals.
Also the Catholic Church (who was also in charge of education) used Latin as a religious and educational language. Therefore, learned men were considered ‘learned’ if they had mastered Latin. Latin was a common language for the world of European Academia.
And most scientist (be it biologist or physicist or chemist or even mathematicians), used Latin to publish their papers. So it is only logical for Carolus Linnaeus to come out with his classification system for living things in Latin or else he would not probably have gained much recognition from the Academia at that time 🙂
It should also be noted that Latin, although widely used, is NOT the language always used for naming organisms. Classical Greek is also used, as well as a combination of Greek and Latin.