The fact that these transitions were so painful doesn't mean that all breaking changes have to be so painful. With Meyers' 'magic wand', the transition is eased quite a bit. But another important component of a smooth transition is a 'carrot', a new feature that's so compelling everybody will want to move to the new use the new version. If a C++ with major breaking changes would also halve compilation time for example, most people would switch in a heartbeat.