Triangulation before export/baking has been a topic discussed on here at length. But if you need a better visual as to why, I present you with this gem.

Something as simple as an errant edge turn can drastically alter mesh profile.
by Jordan Cain
link

Basket Bunny fanart by Carlos Ortega Elizalde
link

by Kad's Egg
link

modeling in 3dsmax /fullquad /sub-d ready by Kad's Egg
link