One one hand, the idea of stop and *boom* you're ready to start cooking is appealing. And indeed there are many places you will be camping where you need to bring the surfaces you'll prepare food on and cook on. Having a galley solves that problem.
On the other hand, there are also places where you might want to cook with friends on a nearby picnic table. And teardrop gallies, unless you have a larger teardrop (we don't) often sacrifice efficiency for size. For example, I personally don't like a built-in sink because: (a) they're usually too small; and (b) you need to plumb them for water; and (c) you often end up with water slopping around everywhere (see a). A pull-out stove is great, but again it needs to be plumbed to propane and you're stuck cooking with it where it is, regardless of the wind. If your galley is small (because your teardrop is small), you might not really have enough counter space to do all the things you need to do to cook comfortably.
There's a third reason a galley is nice, however: it organizes all your cooking supplies in one convenient place. If you don't have a galley you're going to have to stash the stove, cutting boards, plates, pots and pans, etc. somewhere else . . . probably in the back of the car/truck. After teardropping for a few years we've come to realize that in addition to the obvious advantage of a comfortable bed, the second best thing about our teardrop is no more gear chaos in the back of the car/truck!
So our solution, and one you might consider, is a galley that is designed primarily to organize your cooking gear, and can also be configured as a kitchen when needed or wanted. In our case we have a couple of tables that can be deployed in just a few minutes: one to serve as the main preparation and cooking surface, and the other to hole a 7-gallon water jug to create accessible running water. It really only takes a few minutes to deploy the tables, and our "pop-out" kitchen is large enough to prepare, cook, and clean. On the other hand, everything we need for cooking is contained in a few small boxes, which can be easily removed and taken to a nearby table if that's where we want to cook.
Here are a couple of pictures of our galley, in storage mode and kitchen mode: