In this game the action says to discard a card to reroll "one or more dice". That can't include zero. So I'm really unsure as to why that is somehow unclear to some.
It is clear (or... is it?), and we play this way, but I have too much experience with FFG mistakes, misprints, poorly written rules and card texts. Two Mind probes on turn 3 give you a thought, you know.
On the bright side though, the game is really good. And all that whining about CCG/LCG might be nonsense. It seems that you only need half (or even less) of the deck "dice cards" (i.e rare/legendary). It looks like rarity is only for collectors and for dice plastic cost. If you don't have defensive events you might quickly loose. So might be that you can play and spent less than on LCG or X-wing. Also, sometimes you just can't decide which card is better (e.g. Immobilize vs Force choke) and people will be playing simply with those in posession. And this influence deck versatility. And there is of course undeniable trading social aspect. I think tournaments might be particulary fun. We could make two different, strong decks with only 30% starter set, that is a good sign. The only fear is that designers will make some stupidly strong cards and spoil the game.