If you did not mind, i forwarded your question to Bridgestone USA.
I cannot tell you all the ways that the handling would change by
switching tire sizes. I can tell you that Kawasaki engineers
specifically designed that bike with the 160/60R17 size. Also, the
150/70R17 size is designed to be mounted on a 4" wide rim, whereas, your
bike has a 4.5" rim. By putting that tire on your wheel, you will
change the intended profile of the tire.
I cannot recommend changing your tire from the OEM size. If you are
looking to do some more aggressive riding, I would suggest trying a
sport tire like the BT016 instead of the sport touring BT021
Sales Engineering Manager - Consumer Products
Bridgestone Americas Tire Operations
Bottom line: Maybe it would be wiser to stick with OEM. Safety to you is the most Important of All. I have changed tire profile on my BM and it depends largely on how you feel and personal riding style.