Arrays are usually still preferred over collections in the case of primitive types (int[] etc.).

In the unlikely event that I'm modeling something that can be represented as a list of integers AND it's a significant performance bottleneck then, sure, I'll consider the array methods. But I don't recall the need arising in the last year or two.

Enterprise Java stuff just isn't often bottlenecked on that sort of thing. Network latency fills far more of my dreams ;)

The overhead of List<Integer> really can not be overstated, it can approach order 1000% memory consumption, speed is prima facie about half for dealing with collections, but in practice it can be much lower from the GC churn. Even for lists as small as a million entries this can be quite untenable.

You are not seeing different sides of the language but participating in different domains, application/business logic programming vs more system level stuff.