I'd be surprised if this hasn't been requested before.
I thought I might like to give Garmin Connect a try - I currently just use Strava.
I have about 300 backed up .FIT files I want to import into 'Connect' before I can realistically use it.
I am NOT going to import each file one by one. Implementing a batch import is technically simple (you just need to implement a loop).
Ping me back when it's available please. 'Connect' is unusable for me without it.