The game was fully designed around those motion controls, the only reason the stick is even an option is because of whiners, you're going to be at a severe disadvantage if you don't use them.
Is this actually true? I remember Nintendo talking about how the gyro controls worked better than the sticks but I'd assumed that was just PR speak. I just can't imagine motion controls being more effective in a third person game like Splatoon.
Gyro controls are actually very good if you get used to them, most people simply say "yuck" by the mere thought and I can't blame them.
I started learning to use it on Killzone Mercenary on the Vita, because I think the Vita sticks are not good for shooters. And man my game improved a lot. Once you get over the hump, you are definitely faster at aiming than with a stick. Though I am sure its not for everyone. Worth a real shot though.