I'm not the author, but I assume the intent is to allow you to share the JSONSchema definition between the front-end and back-end. For example, a developer could write an annotated .NET class using the Json.NET schema library from Newtonsoft[1], automatically generate the schema for that class, then use this project to compile that schema into an equivalent TypeScript class. Or go the other way around (TypeScript -> JSONSchema -> .NET class). Or start from the middle with a JSONSchema.

Alone, you're right, this project doesn't make much sense, but it's part of a larger community of tools for creating cross-language model definitions based on a common schema language.

[1] : http://www.newtonsoft.com/jsonschema