That requires additional work from the Intent providers. They can no longer be pure JavaScript if they have to request data from other domains, it increases latency as you wait for requests to fetch the item to complete.
Why is it important that intent providers can be pure JavaScript? I would think most providers would be native programs or run in a browser.
As to the latency: if large data isn't available locally, someone will have to take a hit. I do not see why severing this to the provider would be problematic.
If it is available locally, I would hope that the intent provider can retrieve it from cache.
Also, deferring the loading enables optimizations. Suppose I see an image on example.com that I want to share using Flickr. If I send the URL to Flickr, it can retrieve the image from example.com using its fat Internet pipe. If, instead, I have to send the image, I have much more upstream data. Even at home, that can be problematic. Mobile, things are worse.
