Honestly, some of the best brain science ever was by accidental injuries removing some portion of the brain and scientists getting to study the difference. So being able to pick and choose now is ground breaking. It's the equivalent of genetics when we started being able to selectively turn off or insert genes (along with a fluorescent market to know it took).
Those things can be just as crude as each other. Genes (and proteins) can interact in very complex ways so don't be fooled into thinking that 'direct manipulation' of specific parts means you have any idea what's going on.
As a software analogy, think about a very large and complex, undocumented code-base in a bizarre language you've never come across. Your only experimental tool is to pick a line of code, delete/modify it, and then see what happens. As you learn more, you can do refine your experiments but basically, you're still just 'poking it with a stick'.
Any attempt to use the above information will result in a breach of my patent USPO12345678, "A novel method of software maintenance using and IDE and a stick"
Toggling big switches vs smaller switches. Same idea, different scale, different "stick".
What is/are the appropriate scales to study brain function at? Quarks? Molecules? Brain regions? Which ones? All the above? None? We need to know the answer in advance before pronouncing a method "crude", or conversely, "too precise", by some criteria.
We don't know the answer to the scale question but poking "areas" to build up a fuzzy picture of regional function at first approximation is getting us there.
Would the knowledge gained from knock-out/stimulation experiments be more fine-grained if the investigators already had a fine-grained understanding of what they were studying and thus, the cleanest way to study it? Yes.
But breakthroughs are not made where investigators know what they're doing. Breakthroughs are made where nobody knows what they're doing--often crudely, frequently accidentally. The history of scientific advance is messy. Significance of results doesn't map neatly to sophistication of methods/tools.
I wholly agree that neuroscience has a long way to go. But to me that doesn't diminish the achievements of neuroscientists pushing us there, using whatever ethical opportunities available to them.
You can make anything sound daft by expressing it a certain way. The entire history of physics, all the way from cavemen to the LHC, is just a story of smashing rocks together in creative ways and watching what happens.
But obviously it's a lot more than that, and so is electric brain stimulation.
