How do you even learn to read that?
Must be hard, right? Imangine, if you will, the abilities of the people who first cracked it, who figured it out -- and not even Greek, although it is reportedly easier to learn to read and write Greek than it is to speak it. But the Rosetta Stone had a Greek text, a Demotic text, and a hieroglyph text, on the same surface, with approximately the same information, and that allowed a cracking of not one but two scripts. Turns out that even when it was in use, hieroglyphs were hard to use, hard to learn, hard to teach, and just all-around a pain the ass, and that led to our alphabetic scripts, which are easy to use, easy to teach, easy to learn, and at least as flexible as cunieform. Even cuneiform won out over hieroglyphs, probably due to that. Hieroglyphs were used for official texts (and damned few of those were used for things like "enter here" signs at the Egyptian temples) and for reliigious texts on tomb walls and such.
Cuneiform was cracked using old tablets in Akkadian, which is an extinct Semitic language; but the archive from which the translators were working was made up of two different languages, and even before either one of them was figured out, it was possible, by the sequences of characters, to sort them into two piles. Someone fluent in modern Semitic languages made a dent in in the cracking of Akkadian, and in the process came to realize that the script, cuneiform, hadn't been invented for the writing of Akkadian, even though most known texts are probably in Akkadian (that was the language of diplomatic correspondence for a couple of thousand years, most of it written in cunieform, which finally died out about 400 AD). Turned out that the second language in the archive was the originating language of cuneiform, and was Sumerian, a language unrelated to any other known language, and previously unknown from ancient texts, and the people themselves previously unheard of. That must have been a pop-the-champagne moment for a bunch of liberal arts geeks, eh?