Unless you mean actually using the word Enter, technically pressing the Enter key is not a password. Hitting the enter key submits a null or blank password. However, in today's environment it is considered by many to be a very risky practice used by badly informed or outright foolhardy users. However, null passwords can still be used but I suspect Apple has deprecated its use because of the dramatically increased security risk, and the increasingly dangerous, even hostile, internet environment.
As I recall, Cocktail's password behavior is not new and like Onyx has required initial passwords for some time now. The only similar utility I have that does not start with asking for the admin password is TinkerTool System which only prompts for the admin password when a process is initiated that requires one. Personally I prefer the initial password request used in Cocktail and Onyx as the password only has to be entered once whereas in TinkerTool System it has to be entered or re-entered for each procedure that is initiated.
