Don’t be an idiot. Of course it is, and there’s nothing wrong with someone asking you to build prototypes as a designer. It’s just another way to express your vision, and frankly, way better for it than static mockups. Asking if prototypes are important is like asking if wireframes or user research are important. As projects pass a certain size, learn to love prototyping.
Do all prototyping tools suck? Oh god yes. From Pixate’s lack of support for basic features to the mess that is Origami & Quartz Composer, every tool is still terrible in many unique ways, and NONE of them help you actually build an app. God, I miss Flash sometimes.