As the rules stand now, a character who hits on a 2 with prescience (or a similar ability) giving him +1 will miss, because natural hit rolls of 1 always fail.
A model who shoots plasma and rolls a 1 to hit, +1 for prescience, will miss, because 1s always miss, but he won’t splat himself, because the final total is a 2.
Unless he is shooting something with a minus to hit - or unless GW changes the rules to “natural” 1s causing death, th way it is in Kill Team.
Got it. So unless you're overcharging, +1 on a BS2+ unit is generally "wasted" compared to a unit with say BS3+ where there's a bit more benefit.