Semantically, an issue with posting links instead of files is that your users then need to go ahead and upload the file somewhere manually. HipChat takes care o

Semantically, an issue with posting links instead of files is that your users then need to go ahead and upload the file somewhere manually. HipChat takes care of this by adding the file to an S3 bucket when you drag it into the client. Way less hassle, especially for non-technical users.