As an aside, is there conclusive evidence to say that no aether exists, or are we just saying it doesn't exist because a handful of tests were conducted to match what we thought this aether would behave like and the tests came back negative?
Overall, we can't really have 'conclusive evidence' against any mechanism, as long as our observations might possibly be simulated on top of that mechanism. So as far as evidence goes, 'what really exists' might be higher-dimensional strings, or cellular automata, or turtles all the way down, or whatever.
Instead, physics has some number of models (either complementary or competing) that people find compelling, and mechanisms on top of those models to explain our observations. If you did come up with a modern aether theory, you'd have to come up with a mechanism on top of it to explain all the relativistic effects we've observed.
On top of that, if we find something that behaves nothing like what people meant when they said aether, then is it really aether?
It's simpler not to have a medium. The field components transform a certain way under coordinate transformations, and that's all you need.