[badsectoracula]

> Would you like every Windows install to ship with over ten versions of the .NET runtime?

A better approach would be to not break backwards compatibility in the first place.

[Rohansi]

That's what .NET Framework (the one that ships with Windows) tried to do. It usually worked out but you'll still run into compatibility issues sometimes after bug fixes, behavioral changes, etc. because people accidentally build software which depends on quirks.