Why does WWE copyright effect some wrestlers and not others?

WWE copyright laws prohibit individuals using or potraying any WWE intellectual property that is owned by the WWE without their permission. This has seen to effect certain wrestlers when they have worked outside of the WWE like Scott Hall, Kevin Nash, Ed Leslie (Brutus 'the barber' Beefcake). In Scott Hall's case it was just not the name 'Razor Ramon' that was prohibited from using but likeness and style of the Razor Ramon character. These strict laws sound quite absurd as what exactly is considered as WWE thought up creativity or Scott Hall's own individual quirks and likeness. Also, why did characters, that are also quite well known and popular, such as Hulk Hogan, Macho Man Randy Savage and 'Rowdy' Roddy Piper's names, characters and likeness were almost unaffected by WWE copyright when they worked outside of WWE like when they went to WCW. How come some wrestlers get almost stripped of their skin and breathing movements by WWE copyright whilst others seemed untouched by it?