Answer from cs61c-eb (Dae-Yeon Kim 16568138) for Question 4
Strongest argument to stick to the standard is that a lot
of researches had been done on those system.  So already 
a lot of other systems use that standard, which makes the
new co-processors more friendly than having completely new standard.

The argument against sticking to the standard is that
one can have more efficiency by getting out of the standard.  Especially when I would want to design a processor for a specific purpose, I would rather go against the standard.