We should understand Google is business entity and has its own interest to protect. It is just a curtsey gesture that Google does inform us on new technologies and upcoming trends within its set-up.
Most people spend their time today on mobile phones, tablets, smart phones and what have you. It is a large market which had been lying fallow, but today with lots of new encroaches.
no one is forcing you to go mobile. There are businesses that don't rely on mobile users and such that have a significant number of such users to begin with. Who can force them to optimize themselves for something that will not do them much good? Sure, competing sites that make the change might get a boost and surpass them in rankings but its their choice if they will react or not.
So its up to you, if you want to be in good standing with Google or careless.
Of-course, it is you who depend on Google and not vice versa. The choice is yours.