Conflicts are rare and it just seems like an awfully big change to make for something that doesn't really solve the problem and still could result in ordering problems.

It would be silly for plugin developers to have to worry about orders and sub-orders and whatever else when making the plugin, really it is something that needs to be addressed in the plugin system and not with plugins.

The plugin system should simply keep running until all plugins on a certain hook have run and if a STOP was encountered the execution then stops otherwise it carries on. That is all that's needed IMO.