In order for the "latest version" feature to be reliable, they have to avoid users having stale local copies for very long. Thus, they serve those with a much closer expires header, which defeats one of the shared CDN's biggest benefits.
When you reference the full version explicitly, it's served with a +1 year expires header.
// Not cached for long.
// Cached for up to a year.
I don't get the need to gratuitously replicate functionality that's already dead simple. It's a personal project, so I suppose it's as much art as engineering. But of this were a business, I would be very interested in some A/B testing to measure whether you are losing users by not having a one-click way to copy the script code.
Keep in mind that the version fracturing doesn't increase the likelihood of a DNS lookup.