So... I'm NOT an engineer nor do I build successful race bikes, however, this topic comes up often and there are tons of guys who DO build winning motors and are more qualified to discuss the needs for coolers (or absense of), but mostly to parrot them all:
1) first gen is effectively the same motor and doesn't need it. gladius is the same motor and doesn't need it
2) extra points of failure (or rock going through it...)
3) extra weight
4) too small to make any noticeable difference in oil temps
5) RIGHT NEXT TO THE FRONT HEADER so any cooling it attempts to provide is done right next to a thousand degree pipe...