Project Jigsaw (Mark Reinhold’s Blog)

.Net is as big. But consumer software vendors don't mind redistributing it in one blob with their software (often taking most part of the blob), just in case it is not installed on the target system. Like, ATI Catalyst drivers, HP printer drivers&software and whatever else. You would not require a separate action from the consumer, like, "first go to Microsoft, download .Net and install it". You would have to expect an excessively smart consumer to act properly on these requirements.

Sometimes I heard from developers, "how would we distribute our software written in scripting language? We would have to add the whole runtime of this language to each distributed copy, and this would be heavy". Look, .Net software writers have solved the same problem in exactly this way. Very few people seem concerned about this now. Internet is fast and cheap, and digital media capacity is more than sufficient.

In early years of Java (~1996?) I heard about classloader that would load missing classes from the Internet (later this idea had been swept under the carpet as insecure and unreliable one). Why not resurrect it today ? Load missing classes from the vendor only if you use them, cache them locally, sometimes expire/refresh them. Today, encryption, certificates and digital signing are common things.