As someone using Moodle daily I will like to suggest a small improvement. The calendar view on the page displays a course name in the event title like so:
However, for the calendar export:
This poses a problem with assignments with enigmatic names like "LA1 is due". This surely confuses students and discourages them from using the subscription feature.
I believe the easiest solution here will be inclusion of the course title in the title of the even, or even in the "notes" field for the event.
Briefly looking at the code it seems like this feature will be a simple patch. If I'm not missing anything I can probably offer the path after getting more familiar with Moodle development process.
While the web version presents the course name before the event name, I believe in the calendar export/subscription the course name should be appended after the event name. The reason being the course names are often long (e.g. "BIO 2280/2810 1A/1B/1C/1D/02: Microbiology"), which will cause calendar to be even more confusing if name is appended before the event name: