Graph isomorphism isn't that important practically (subgraph isomorphism is, but it's NP-complete and, IIRC, APX-hard as well) and the hard graph cases don't come up much in practice (despite being a relatively large percentage of random graphs, AFAIK). I think it reflects a difference in how mathematics is done; the quasipolynomial result was first presented at a conference, not in a paper, which definitely wouldn't have been the case 20 years ago.