If mind was matter and every mental act a mechanical resultant of neutral states,of what use is consciousness?

consciousness is a state where you can operate your body knowingly without banging into everything like a zombie.

3 things exist in the universe. matter, consciousness, and energy. you will find all 3 in everything you see. they are inseparable.

Mind is matter and only mind can attribute utility to anything. It seems you equate mind with consciousness so the question is equivalent to asking what the use of matter is. Basically it is for whatever use I decide and may have a variety of used as otherminds may decide alternately and has an indeterminate number of possible uses not brought into practice. Perhaps you are seeking a different kind of an answer but this would require more attention to the definitions of terms of the question.

“What use is consciousness”
Do you presume everything has a purpose? We assign purpose, none is inherent or god-given.
Consciousness is a concept we use to describe our ability to generate and manipulate abstract concepts. All animals can do this to some extent… some are more intellectually evolved than others.
It is an illusion that your consciousness is something existent in its own right… that illusion has led to concepts like souls, or even minds.

Not ‘neutral’ neural, neurosis, neurotic …. Purpose is the use for consciousness, and of that, self consciousness. Not having the concept for ‘energy’, the word ‘matter” would mean nothing more than ‘nothing’.
The Will is positive, the Judgment is negative.
http://www.marxists.org/reference/subject/philosophy/works/en/berkeley.htm
Bishop George Berkeley (1710)
Of the Principles of Human Knowledge.
80. In the last place, you will say, what if we give up the cause of material Substance, and stand to it that Matter is an unknown Somewhat – neither substance nor accident, spirit nor idea, inert, thoughtless, indivisible, immoveable, unextended, existing in no place ? I or, say you, whatever may be urged against substance or occasion, or any other positive or relative notion of Matter, hath no place at all, so long as this negative definition of Matter is adhered to – I answer, you may, if so it shall seem good, use the word ‘Matter’ in the same sense as other men use ‘nothing’, and so make those terms convertible in your style. For, after all, this is what appears to me to be the result of that definition – the parts whereof when I consider with attention, either collectively or separate from each other, I do not find that there is any kind of effect or impression made on my mind different from what is excited by the term nothing.

Consciousness means God or Krishna Consciousness. Otherwise it is only due to the material illusion (Maya) which are just coverings or veils over our consciousness so we do not realize who we actually are. So when we use our mind in the service and thought of God then we are actually conscious otherwise we are in illusion. (Maya) the mind can be purified to be actually conscious. The consciousness can be covered by the impure mind. Yet both are needed.

Every things can be programed even consciousness , and somebody else using our consciousness for us .