Yes, often it is to my advantage to only use the 2 instead of all 8. No one has yet given me an answer as to why not that hasn't simply been "it's the rule", or "it's to my advantage" which is closely related to "it's the rule".
RsBaby: Checkmate in chess is checkmate in chess. It is how you win. It can be proven with any checkmate that you cannot resolve the check, ending the game. Playing a move that's against a rule in backgammon isn't the same. It would be a better analogy to say "move your piece to capture my king on the first move because you can". And even that is not the same. Pieces in chess move a certain way through the whole game. It would be fine if every piece could move like that through the whole game, although it wouldn't be chess.