Guys, lets say that i have a z threaded rod pitch 2mm,

Guys, lets say that i have a z threaded rod pitch 2mm, if using 1.8 steppers i can go full stepping and get 100 steps per mm, thats 0.01mm per step. So, im on the safe side if i wanna print 0.1-0.2-0-3 mm layers, right?.

Then, given that scenario, why i would wanna use microstepping?

It will run smoother.

From this post: http://www.micromo.com/microstepping-myths-and-realities.aspx

“In summary, although Microstepping gives the designer more resolution, improved accuracy is not realized. Reduction in mechanical and electromagnetically induced noise is, however, a real benefit. The mechanical transmission of torque will also be much gentler as will a reduction in resonance problems. This gives better confidence in maintaining synchronization of the open loop system and less wear and tear on the mechanical transmission system.”

I have heard microstepping reduces the amount of noise the motors make.

@Alex_Wiebe nice link. It gives great explanation.