Engine sliders are a must! A bit expensive though...
Agree, though I have never had them on any of my bikes in the past.
I think these (originals) do not represent the best value, and i'm happy to go with some from R&G or what ever brand available.
Of original equipment, i'd look for the bags, fly screen and tank pad. Maybe an iPhone mount, too

I've got an USB charger from my previous bike, so wont need that.
I found out, that there is an official power outlet under right hand air intake.
What about heated grips - I think I saw some mentioned as original accessory at one point, but not seen them on Yama's site.
Riding to work this morning, just confirmed, that heated grips should be much much much higher on the wishlist for now

*BBRRRR*