Bonus Ceremonies - INT only?

Is it intentional that ceremonial classes only receive bonus ceremonies based on Intelligence?

I was expecting the Ecclesiastic and Runemaker to use WIS instead of INT, as per their Prime Requisites.

It's absolutely intentional. 

Repertoire size is always modified by INT, regardless of class because having a large memory is a function of INT.

Ceremonal throw is always modified by WIS, regardless of class because WIS measures divine favor by those empowering the ceremony, willpower of the caster, mindfulness and attention to detail, and so on.