The below is for in project copy/paste and cross project copy/paste:
Copy Paste should ask you what you want to include in your paste. For users that want pred/successor relationships to be pasted then select, if they want resources, dates etc then they can select as part of the paste. At the very basic level it should not default paste pred/succ relationship as this can completely screw up a users project work plan and cause them to delete the entire thing and start over. This CR is looked at as a extremely high priority for our user community due to the damage it has done and negative impact to user experience.