I'm perplexed that the other commenters identify ether theory as a fringe theory. I suppose, by their definition, Newtonian mechanics is also a "fringe theory" simply because it is outdated, and yet nobody is out to debunk Newtonian mechanics (in fact we teach it in schools). "Debunking" ether theory and obscuring its pedagogical utility is clearly an emotional pursuit for these people. It's hard to understand where this religious mentality about ether theory comes from, except in the context of a century of propaganda, as you pointed out. The attitude is clearly political and inappropriate (yet all too common) on Wikipedia.I agree. If you think that aether theory was somehow wrong or unscientific, then read J.C. Maxwell's 1878 article in the Encyclopedia Britannica. He did not know that the aether had to be invariant under Lorentz transformations, but his essay holds up pretty well.
Here is what Lorentz's famous 1895 relativity paper said. After dismissing some aether theories:
It is not my intention to enter into such speculations more closely, or to express assumptions about the nature of the aether. I only wish to keep myself as free as possible from preconceived opinions about that substance, and I won't, for example, attribute to it the properties of ordinary liquids and gases. If it is the case, that a representation of the phenomena would succeed best under the condition of absolute permeability, then one should admit of such an assumption for the time being, and leave it to the subsequent research, to give us a deeper understanding. That we cannot speak about an absolute rest of the aether, is self-evident; this expression would not even make sense. When I say for the sake of brevity, that the aether would be at rest, then this only means that one part of this medium does not move against the other one and that all perceptible motions are relative motions of the celestial bodies in relation to the aether.Einstein said essentially the same thing in 1905:
The introduction of a “luminiferous ether” will prove to be superfluous inasmuch as the view here to be developed will not require an “absolutely stationary space” provided with special properties, nor assign a velocity-vector to a point of the empty space in which electromagnetic processes take place.Poincare wrote in a popular 1902 book that the aether is a convenient hypothesis what will someday be thrown aside as useless. The lesson from relativity was not that the aether was wrong, or unscientific, or nonexistent, or exemplary of 19th century thinking.
The lesson was that theories based on motion against the aether were disproved.
The aether is sometimes defined as whatever transmits electromagnetism. If it is Lorentz invariant, then it poses no problem for relativity.
The existence of a preferred frame poses no problem either. The cosmic microwave radiation can be used to define what a rest frame is, so there is nothing wrong with that concept.
There was a time, maybe a century ago, when one could make fun of ancient scientists for lacking the imagination to understand that a vacuum might be empty space. But a vacuum is not really empty in today's theories either.