Since ArangoDB competes with MongoDB, that would be nice to have something like GridFS implemented in driver.

In GridFS documentation, GridFS is defined as:

GridFS is a specification for storing and retrieving files that exceed the BSON-document size limit of 16 MB

I know ArangoDB doesn't have 16 MB limit but GridFS is not just for exceeding document size limits. It is used to store files in chunks. This will have some benefits for some use cases. For example putting profile picture to ArangoDB collection will make developers life much more easier. In past, I've used to store TBs of data in MongoDB that is accessed occasionally and it saved me lots of time to look for a distributed file system. I'd like to see ArangoDB drivers also implement GridFS. In fact, I may try to implement it if this gets accepted.