What is the rationale behind the Embraer 190's control column design?
I think it's quite similar to a steering wheel with your hands a bit to the upper half. You rest your hands onto the yoke with this variant, as compared to the other ones where they are vertical and inclined to slide downwards. 

While I'm certainly not sure, it could be a sensory thing as well, perhaps allowing better feel for the position as you are putting less energy into your arm and tiring it out less.

I think it's a minor design detail and had it been uncomfortable/ problematic they would have got rid of it pretty quickly.

Embraer Angled Yoke

Bombadier Vertical Yoke