To some of us, translating a book can look like a lot of drudge work. (Think your translation assignments for French 101 are bad? Well, just try translating The Flowers of Evil, The Inferno, or Eugene Onegin in its entirety.) But looks can be deceiving. As someone who's had to translate world literature at several points in his career, I'll be the first to admit that there's an irritating "check this, check that, then double-check the dictionary" feeling to the whole task. Ah, but once you get beyond this, translation starts to be a matter of high artistic and intellectual value. At times, it can be as challenging as writing your own literature.
Don't take my word for it. Look, instead, at all the great authors who have doubled as translators. Look, also, at the PEN Prize, the Scaglione Prize, and other big-name translation awards.
But what is it, exactly, that makes translation a highly sophisticated activity and not a mere chore? I have a few ideas. Some kinds of writing are so difficult to take out of their original language that a translation, any translation, requires immense reserves of creativity and resourcefulness. Poetry is widely thought of as untranslatable, and some works (Flaubert's novels, James Joyce's prose experiments) hinge on effects of sound and pacing that a new language might not capture. But translation isn't all about demure library work. Like creative writers, translators compete with one another: for readers, for money, for commemoration, and for sheer excellence.
Those are a few reasons, but there are plenty more. Why, in your opinion, is translation an intellectual activity of the highest order? Or is it? Maybe it is all a big version of those French 101 assignments. The PEN and Scaglione people would tell you otherwise, but, well, it takes all kinds.