Tolkien wanted to do something about the absence of a real English "myth", discounting Arthur and the Knights. He wanted to create a world that could have existed in the far past, so long ago that nobody remembers it anymore.
That is why the ocean is on the left, why the Shire is placed where it is, and other geographical features. Harad is most likely supposed to represent Africa. (I believe Tolkien both confirmed and denied that, actually)
He even had his own Atlantis-type legend: Numenor, buried beneath the sea when the Numenoreans tried to overthrow the gods.
However saying Tolkien stole the Middle-Earth map seems slightly ridiculous. Despite the above evidence, Middle-Earth really doesn't look all that much like the Europe-Africa region, except for the glaring left coastline. And really, that was his purpose: to create a world that was similar to our own.
I personally don't care that Paolini used a map very similar to Tolkien's own; I do think it would not have been too much work to come up with something original, but hey, idk.