You can make a damn good IPA without any crystal malt, but that's not the only way to go about it. And even then, I think you still need something else to give it some malt backbone. My IPA is 2-row, Munich, Victory with no crystal at all. You could also probably make a solid IPA using 100% of a flavorful base malt like Maris Otter, or maybe a good continental Pilsner.
I've had a lot of IPA's and (even more often) IIPA's that have an unpleasant sweetness to my palate. I always used to write them off as having too much Crystal malt, but I've started to come over to thinking that it is more from underattenuation. The higher alcohol content of big IPA's and IIPA's already lends the impression of sweetness. Once you add hops and if you have any sweetness left in the beer, it starts to become a bit cough syrupy.
In the end, good fermentation always levels the playing field and is way more important than recipe design.