The Drag and Drop markers and the Drag and Drop onto image additional question types plugins are among the 20 Top plugin downloads in the last 2 months
The stats seem to show a tendency for an increasing number of downloads over time.
I like these plugins a lot, and I think that these two plugins (as well as many others), contributed by the Open University, have been thoroughly tested, are well written and well maintained. So, in my very personal opinion, I think they would make prime candidates to consider for suggestion for inclusion into a future Moodle core.
If these (and all other) additional question types made by the Open University were included in Moodle core, all Moodle sites using that branch could use them very easily (no extra expenses/fuzz for installing them), which will contribute to their use in both formative and summative assessments. This will greatly improve the academic use of Moodle.
I have been translating the Moodle Docs for these additional question types into spanish, so that spanish-speaking teachers can easily use many of these question types. The original plugins documentation in English, hosted at the OU site, is very comprehensive and easy for a novice to follow.
I think that the next logical step would be to discuss the pros and cons of this subject; for example, in this forum, before adding an issue in the tracker and lobbying for votes in the tracker as a very desirable and convenient new feature of a future Moodle branch.
I will be looking forward to reading the opinions of the many users and admins who have tried these plugins.