I don't see how the mirror blocks anything from the left unless your car is a right handed driver? And close objects can't be blocked by the mirrors. But from a distance the super large Z mirrors do hamper vision from views over 40ft from the car which can be an issue with a car coming at you at a high rate of speed.
I feel the Z mirrors are clumsy, I notice the same issue in the juke. I don't know why people on this site are always sending people to prius' and family cars because of visibility issues with Z mirrors or similar things. From vette to ferrari, I have seen a plethora of race ready mirrors with a lean frame. Where is it written that fat bloated mirrors are the premier feature of a sports car???
Now, OP, my suggestion to you is start looking into aftermarket designs because nissan isn't going to re-engineer mirrors into a sports car that can barely break 10k units in sales. 2012 was the update year and the Z is not getting any updates. That info in itself speaks for your suggestion to nissan for redesigning mirrors. Go to
Nissan Cars, Trucks, Crossovers, SUVs & The Bottom Line Sales Event | Nissan USA and you will notice they still have the 2010 Z on the advertising roster with the 2011 and we are 2 months away from the first 2012's rolling out. Aftermarket is your only solution. As far as close objects be more careful. It seems you are 5'8 but your legs are long and u have a shorter torso. So u may be compromised some with your overall view?