I think the problem is that often you really do want to know if customer is nil. The nice thing about having to explicitly specify this is that you localize the effects - and make it clear in your code that you want this 'pass-through' behavior in a specific part of your code.

If you wanted this behavior everywhere, you could just include this code

  class NilClass
    def method_missing(method, *args)
      nil
    end
  end

But I think this would cause more problems than it would solve.