Moroni provides an answer to this question. "32 And now, behold, we have written this record according to our knowledge, in the characters which are called among us the reformed Egyptian, being handed down and altered by us, according to our manner of speech. "33 And if our plates had been sufficiently large we should have written in Hebrew; but the Hebrew hath been altered by us also; and if we could have written in Hebrew, behold, ye would have had no imperfection in our record. "34 But the Lord knoweth the things which we have written, and also that none other people knoweth our language; and because that none other people knoweth our language, therefore he hath prepared means for the interpretation thereof." Apparently the version of Egyptian that was used for the plates on which Moroni was writing was a more compact language than Hebrew is. Thus, Moroni can get more on a single plate using that language than he could using Hebrew. Let us also consider the idea that writing on plates is not the same as writing on paper. When writing on paper, you don't have to push very hard. You only need to touch the tip of the pen to the paper for the ink to flow. However, when writing on metal plate, the writer has to push hard enough for his stylus to actually leave an easily visible scratch on the plate. Anyone who has ever written a significant amount of text with a pen or pencil knows how tiring it can get. Your fingers begin to ache with fatigue from holding the writing implement. Now, imagine how much faster that would come on when writing on plates. When you take these considerations into account, it becomes pretty obvious why someone would prefer to use the most compact language available to make a record on metal plates. It allows the writer to get more on each plate and saves wear and tear on the writer's fingers. By the way, there is evidence of this practice of ancient Hebrews using modified versions of Egyptian to make their records. http://www.deseretnews.com/article/705379190/Reformed-Egyptian-an-evidence-for-Book-of-Mormon.html