It's a marketing thing, IMO, like Interlac for the Legion of Superheroes fandom. By putting snippets of information in a format where a reader has to work to translate it, you make them feel invested in that information once they get it. They put work in to get it, making it light up the reward centers in your brain when you get it. Even if it's the sort of information that you would not have found particularly compelling if it were written in regular text, your brain has tricked you into thinking of it as a 'reward for work done,' and you now value it more highly. It's the same reason why some religious texts are written as parables, to engage the reader and make him feel some sense of 'owning' the message. He's just not having information poured into him, but he's having to tease out the meaning for himself, and since the answer is now coming from in his own brain, he feels like it's more valuable (and trustworthy) than something somebody else told him.
It's all clever marketing, and I loved it, as a Legion fan, and have zero interest in translating it for myself in the case of Krakoan, and just read other people's translation, 'cause I'm way too old for this stuff.
In-story, it also has all sorts of potential for shenanigans. What if it is later revealed that Krakoan language doesn't have words to describe some very specific things that Xavier doesn't want people thinking / talking about? Has more words to describe (and precisely describe) things he *does* want people thinking and talking about? It could be part of a huge thought control scheme, like something out of 1984, where certain words have their meanings changed, and other words are deleted entirely, while new words are coined, all to manipulate the people using this language and render them incapable of articulating or communicating ideas that the government doesn't want to spread. We've seen no evidence of that, yet, but I'd hardly put it past Xavier. He's pretty clever, and can tap into Cypher's linguistic abilities telepathically, if he needs help Tolkeining up a new language (granted, this is comic books, so it shouldn't matter that he's never studied linguistics, since comic-book scientists are just arbitrarily good at *everything*, but I like fishing for that No Prize).