I think the standing 8 should be an option for sure asnd I mean an option you can turn on or off. I personally don't like it, but recognise it's in the rules of some boxing authorities so it should be included in the game.
Taking an knee? Definitely!
And one other thing. The abilitiy to keep wailing on your oponnent until the ref drags you off him after you've landed a knockout punch. It would make for really exciting knockout or knockdown moments. The best I can do in the game at the moment is land a maximum of 4 punches once the oponent is KOed. In real bxing, the combination of punches being landed is sometimes what keeps the KOed fighter vertical even when he's actually out and the ref has to jump in between them or fling the attacking fighter across the ring.