I tend to agree with you, although I think of this as a strict limitation of empiricism.
We expand scientific knowledge through the creation of universal experiences that are (in principle) available to anyone- replicable experiments- and on the models that follow from those experiences. Consciousness, in contrast, is an experience of being onesself (and in exceptional cases, the experience of being aware that one is aware of onesself, and on down the rabbit hole). What would it mean to create the experience of being a particular entity, accessible to any observer? That question looks suspiciously like gibberish. The excellent and admirable What is it like to be a bat? develops this idea quite a bit.
But hopefully, this problem becomes fairly trivial even if it doesn't disappear as such. We can certainly notice that human bodies tend to seem conscious and that shoes tend not to, and by developing AI from a (gulp) basically phenomenological perspective we can create a future we have every reason to believe is rich with selves and perspectives, no more a leap of faith than biological reproduction. We just won't be able to point a consciousness-detecting machine at them and wait for it to go 'ping'.
Having been able to firsthand experinece what it is like to be an echolocator I don't find the question gibberish at all.
Even with ordinary evidence you don't have access to other peoples experiences of the aparatus. That is I will never know what the thermometer will look to you. And if I am like color blind I can never have quite same experience. But still we get compatible enough experiences to constuct a "thermometer reading" that is same no matter the subject. In theory it should not be any more harder to construct such experiences that stand for experiences rather than temperatures.
In response to the classic Mysterious Answers to Mysterious Questions, I express some skepticism that consciousness is can be understood by science. I postulate (with low confidence) that consciousness is “inherently mysterious”, in that it is philosophically and scientifically impenetrable. The mysteriousness is a fact about our state of mind, but that state of mind is due to a fundamental epistemic feature of consciousness and is impossible to resolve.
My issue with understanding the cause of consciousness involves p-zombies. Any experiment with the goal of understanding consciousness would have to be able to detect consciousness, which seems to me to be philosophically impossible. To be more specific, any scientific investigation of the cause of consciousness would have (to simplify) an independent variable that we could manipulate to see how this manipulation affects the dependent variable, the presence or absence of consciousness. We assume that those around us are conscious, and we have good reason to do so, but we can't rely on that assumption in any experiment in which we are investigating consciousness. Before we ask “what is causing x?”, we first have to know that x is present.
As Eliezer points out, that an individual says he's conscious is a pretty good signal of consciousness, but we can't necessarily rely on that signal for non-human minds. A conscious AI may never talk about its internal states depending on its structure. (Humans have a survival advantage to social sharing of internal realities; an AI will not be subject to that selection pressure. There’s no reason for it to have any sort of emotional need to share its feelings, for example.) On the flip side, a savvy but non-conscious AI may talk about it's "internal states", not because it actually has internal states, but because it is “guessing the teacher's password” in the strongest way imaginable: it has no understanding whatsoever of what those states are, but computes that aping internal states will accomplish it's goals. I don't know how we could possibly know if the AI is aping consciousness for it own ends or if it actually is conscious. If consciousness is thus undetectable, I can't see how science can investigate it.
That said, I am very well aware that “Throughout history, every mystery, ever solved has turned out to be not magic*” and that every single time something has seemed inscrutable to science, a reductionist explanation eventually surfaced. Knowing this, I seriously downgrade my confidence that "No, really, this time it is different. This phenomenon really is beyond the grasp of science." I look forward to someone coming forward with something clever that dissolves the question, but even so, it does seem inscrutable.
*- Though, to be fair, this is a selection bias. Of course, all the solved mysteries weren't magic. All the mysteries that are acctully magic remain unsolved, because they're magic! This is NOT to say I believe in magic, just to say that it's hardly saying much to claim that all the things we've come to understand were in principle understandable. To steelman: I do understand that with each mystery that was once declared to be magical, then later shown not to be, our collective priors for the existence of magical things decrease. (There is a sort of halting problem: if a question has remained unsolved since the dawn of asking questions, is that because it is unsolvable, or because we're right around the corner form solving it?)