This is a very good question and suggestion. At this time I have no knowledge of this being added to Express for future releases.
Activities saved to the microSD card will need to be manually uploaded into Garmin Connect currently. Please refer to the following FAQ:
How do I upload activities recorded to the microSD card on my Edge 810, 800 or 510?
Shane
So you haven't been switched to Modern yet. In that case, there should be an "Upload" button on (almost?) every page. Just use that.