We don't have an outdoor kitchen. We do most of our cooking outdoors but it's about 95% on the Bar-B-Que. We have a 2 burner coleman propane stove but we rarely use it; only use it for boiling a pot of water for noodles or something. We have a large electric frying pan and a elec griddle also that we use; mostly for a large batch of scrambled eggs and pancakes. A 2 burner stove wouldn't be big enough for what we are cooking.
I don't have the need for an outside kitchen but if you find that you are using a 2 burner stove and sink outside regularly, than it would probably be useful to you. But you got to decide that for yourself. It's like everything, a tradeoff, you give up space inside for the outside kitchen, do what works for you.