Replace get() with orElse(null).
First of all, consider that the check is complex and probably relatively time consuming to do. It requires some static analysis, and there might be quite a bit of code between the two calls.
Second, the idiomatic usage of the two constructs are very different. I program full time in Scala, which uses Options much more frequently than Java does. I can't recall a single instance where I needed to use a .get() on an Option. You should almost always be returning the Optional from your function, or be using orElse() instead. These are much superior ways to handle missing values than throwing exceptions.
Because .get() should rarely be called in normal usage, it makes sense for an IDE to start a complex check when it sees a .get() to see if it was used properly. In contrast, iterator.next() is the proper and ubiquitous usage of an iterator.
In other words, it's not a matter of one being bad and the other not, it's a matter of one being a common case that's fundamental to its operation and is highly likely to throw an exception during developer testing, and the other being a rarely used case that may not be exercised enough to throw an exception during developer testing. Those are the sorts of cases you want IDEs to warn you about.
The Optional class is intended to be used when it is not known whether or not the item it contains is present. The warning exists to notify programmers that there is an additional possible code path that they may be able to handle gracefully. The idea is to avoid exceptions being thrown at all. The use case you present is not what it is designed for, and therefore the warning is irrelevant to you - if you actually want an exception to be thrown, go ahead and disable it (although only for this line, not globally - you should be making the decision as to whether or not to handle the not present case on an instance by instance basis, and the warning will remind you to do this.
Arguably, a similar warning should be generated for iterators. However, it has simply never been done, and adding one now would probably cause too many warnings in existing projects to be a good idea.
Also note that throwing your own exception can be more useful than just a default exception, as including a description of what element was expected to exist but didn't can be very helpful in debugging at a later point.