I suppose no one has answered my question above because no one (yet) has a handy list of the essential, minimal assumptions of the theory of "luminiferous aether". Though perhaps I didn't describe my question well enough. It was: What assumption about the aether caused it to be disqualified?

During my drive home, I had some time to recall my motivations for wondering about the theory of aether and whether it is really dead or just out of style..

From what I understand of what light is -- mainly from discussions here on Less Wrong -- light is what happens as the electromagnetic field gets updated. Suppose you have an electron at location (x,y). This creates an electromagnetic field centered at (x,y). Then you move the electron to position (x',y') and the new electromagnetic field is centered there. The whole electromagnetic field has to shift by this much. But the field can't shift throughout the whole universe instantaneously. The change in the electromagnetic field propagates at a finite speed from the new position. We see this 'fixing' of the field as a light wave propagating through space.* Naively, I view it as a disturbed mesh that rights itself one kink at a time.

Is this mesh 'real'? If it's not real, what is the electromagnetic field? What is changing and getting fixed over time? To me, the question of whether the aether is real is the same question. Isn't there something there? But if not, how can it work?? I don't mind if the answer is something more abstract than a type of matter/particle. It just seems that if information is moving something must be carrying it.

* We see a lightwave by catching it, which means we change the electromagnetic field in exactly the right amount to counter the defect and stop its propagation.