I'd say in any sufficiently complex program, random testing is not only useful, it's essential, in that it will quickly find bugs no other approach would.

Even better, it subsumes many other testing paradigms. For example, there was all sorts of talk about things like "pairwise testing": be sure to test all pairwise combinations of features. Well, randomly generated tests will do that automatically.

I view random testing as another example of the Bitter Lesson, that raw compute dominates manually curated knowledge.