The importance of Subash Khot's paper on the <A href="https://doi.org/10.1145/509907.510017">Unique Games Conjecture</a> derives primarily from the significance of the conjecture that he introduced, which has stimulated an enormous amount of research in complexity theory.  It might not quite fit your criterion because the results in the paper are not trivial, but certainly the conjecture itself is now regarded as the main contribution.