There is already so much fictional/scientific/medical/... literature in English so why doesn't everyone in the world just speak English? There are so many dialects and variations of English that one has to often understand. Why bother with another language at all? After all, the purpose of inter-human communication is nicely served by English. What is with all those crazy people who speak other languages - especially when they are related to English (say Indo-European group of languages).
Sorry, I misunderstood the question. You said what? Why are all query languages not just SQL? What is with this LINQ syntax anyway. Annonyingly like SQL but different? How dare you? What were you thinking? Why didn't you use T-SQL/PL-SQL/my-favorite-dialect-of-SQL?
Perhaps I (or others) could answer the question about specific features of LINQ syntax and why certain design choices were made for the minor matter of being consistent with the domain (objects) host programming language(C#/VB) and the environment (CLR, VS IDE). As for the more fundamental question, are you still looking for an answer? Really?
What do I know, I am not a native English speaker or a native SQL speaker for that matter :-). Although I use both the languages extensively and like them both a lot I don;t feel the kind of attachment that would lead to such questions.