The capitalist state and it's forces in the form of Police and Military primarily exist to protect the private property of the rich. All other functions are secondary.
Lenin loses me with his Dictatorship of the Proletariat. Personally, I think that demonstrating such lack of faith in humanity and in the power of workers to take things into their own hands is fundamentally at odds with the sort of organically arising communist-style models Marx and Engels are talking about.