Where I ride, the things work opposite... First they expect from you to ride and then to think or understand. First they expect from you to jump and then to know the dressage basics.
That's briefly my story as well. I was jumping and that's all, no dressage. I was even competing on show jumping, without having dressage lessons.
And one day, I realized that the horse I was riding this period was kind of... half blind. Cataract problem I think, cause she was getting older.
So I quited from jumping and we started dressage, in order to have some specific exercises to do. Since then, I ride dressage mostly because the horses I ride have problems to jump (eyes problem, legs problem, etc) so we do light dressage work and we all are happy.
What I have noticed - of course, is that my jumping has been improved a lot, especially when jumping over 1.10 courses - when I have the chance of such horses.
I like dressage, it's more calm, more demanding in daily basis and more fun at competitions. Jumping is still first in my heart, but I enjoy both types of riding equally now :)