Why is Greece not called in English by the name Hellas? [duplicate]

The Greeks call their country Hellas and themselves Hellenes.

The names Greece and Greek are of Roman origin and were adopted from Latin Graecus into old High German as Crêch and then in all Germanic languages the name was fashioned after the Latin - Old English Grécas. (See OED extract below)

It has been the policy of the international community for many years to name new countries, (and rename old ones), to correspond with the way they are known to their own government and population. Thus Abyssinia became Ethiopia, the Gold Coast became Ghana, Rhodesia became (after partition) Zambia and Zimbabwe. (For a more complete list of name changes go to http://www.conservapedia.com/Renamed_countries.)

Since there may be some evidence that it was only colonists (presumably from Rome to Euboea) that assigned the name Greece, why do we continue to use that name and why not Hellas? After all we no longer refer to the USA as The thirteen colonies.

Forms: pl.OE Cré(a)cas, Gré(a)cas, ME Greckes, Orm. Grickess, ME Greks, Grekis, ME Grekys... (Show More) Etymology: In branch I: The Old English Crécas plural, corresponds to Old High German Chrêch , Chriech (Middle High German Kriech ), Gothic Krêks < *Krêko-z , an early Germanic adoption of Latin Graecus , plural Graecī (see below), the name applied by the Romans to the people called by themselves Ἕλληνες . The substitution of k for g is commonly accounted for by the supposition that the Germanic initial g , when the word was adopted, still retained its original pronunciation /ɣ/ , so that k would be the Germanic sound nearest to the Latin g . In all the Germanic languages the word was ultimately refashioned after Latin, with change of k into g ; hence Old English Grécas plural beside Crécas , Middle Dutch Grieke (Dutch Griek ), modern German Grieche , Old Norse Grikkir , plural. In branch II the noun is an absolute use of Greek adj. The Latin Graecī is < Greek Γραικοί, said by Aristotle ( Meteor. i. xiv) to have been the prehistoric name of the Hellenes in their original seats in Epirus. The word is apparently an adjectival derivative of Graius, which is used in Latin as a poetical synonym of Graecus. Recent scholars think the name may have been brought to Italy by colonists from Euboea, where there is some evidence of its having existed: see Busolt Gr. Gesch. I.2 198. (Show Less) I.

The name Greece is probably due to the dominance of Latin during the Middle Ages. Latin was the language of the Church and of science. Nicolaus Copernicus wrote his De revolutionibus orbium coelestium (On the Revolutions of the Heavenly Spheres) in Latin, published in 1543.