I can't see how realistic the actual Strait of Hormuz map is either. As always with the DCS environment we have discrepancies between map, planes and assets ; the timeline is blurred and/or wrong. DCS World is as good as what we make of it (any additional help from ED is welcome though).
Regarding the Marianas, if we take into account the latest Pentagon studies, they confirmed previous analysts reports that the US would be defeated by China in case of an open armed conflict - the case of Guam is treated in these scenarios (these informations have been leaked last week, let's wait for the Pentagon's 2020 China military power report, due for this summer, and read it). While these studies is also a way for officials to gain additional funds for their branch, it is a stark reminder that these scenarios are not pure science fiction or a distant threat in time.
Using the Marianas islands as a theater of war is as good as using the Caucasus or the Strait of Hormuz maps or even better as we will finally have a true blue water engagement.