One of my players has a bit of a problem with the new initiative system, and the fact that the party can choose in what order they use their initiative 'slots'. While he understands 'realism' is a relative thing in fantasy roleplaying games, this new initiative system urks him, because it seems unrealistic that a character with slower reflexes would get their turn before a character with faster reflexes. Sure, you could say that the faster PC is 'slowing down' for the other, in order to let them go first, but that would allow the opposition to possibly get in a blow.
So why do you think the new system allows players to choose their initiative order? And how can it be justified in terms of 'realism', if at all?