By not using the LoginRequest class you're bypassing any validation that would be done for that request. It's not ideal, but at the end of the day you're still attempting (->attempt()) against the Guard/$auth object, so it's not doing you any harm.

However, this is a great feature of the new L5 codebase. You don't have to worry about handling validation (one of the major components of any application) at the controller level. Thereby reducing the number of lines you have to write yourself (and you'll find yourself repeating ALL the time).

I can't understand why changing out the request object would resolve the auth class (which is called Guard) for you, though. You haven't changed anything in that respect.

Jeffrey Way has outlined some details surrounding it here -> https://laracasts.com/series/whats-new-in-laravel-5/episodes/3