i don't believe falcon needs the jump. his recovery's much better this time around.
but for ganon, any bit can help. i haven't tried the backwards reverse neutral B for momentum in B+, so perhaps that's still reliable, if very easily gimpable, but his recovery's terrible. he's not a fast character in the air, so giving back his second jump, which mostly blows anyway, wouldn't be broken. it'd merely be somewhat akin to how link's upB was extended a bit.
his recovery would still be terrible, but it would be Ike 'terrible' instead.
Edit: concerning 'variety' for characters. this is a great thing. free-form playstyles and comboing is what makes smash so great! however, always taking into account that variety in too many situations can spell disaster if this variety isn't confined to very specific situations.
in this case, the two best situations to describe giving back their jumps would be off stage downB gimping and recovering from a very horizontal zone. in ganon's case, the first option might be a dangerous one to decide upon, but, in fact, he can already do his downB offstage and recover from what i know of (if i'm wrong, then that'd explain why i never see it.) and if not then this would simply add to his near stage gimping power, which has always been good (Stomp, utilt...kinda, uair). in the end, this variety in gimping power, but his variety was already great there.
as for falcon, this also would add to his own gimp variety, but, more importantly, it would add to his recovery, which i've already said to be good, better than its counterpart in melee. as an alloffensive character, that's heavier than he looks, another option for recovery can approach being too strong. i thought falcon's recovery was Meant to be gimpable? otherwise, why wouldn't his uB be like ganon's shadow shoryuken?