jiggs and lucas are very different characters, from 2 different games with differing mechanics.
i main jiggs and have played some p. good marths, and I can tell you the only way to win that fight is to just bait marth until he ****s up by floating in and out of his range repeatedly and go for a punish. you need a large stage with lots of platforms to win that fight. (dream land is really a godsend for that matchup @.@)
lucas doesn't have that kind of option. he's all momentum all the time, so if he wants to go into a characters range, he's gonna stay in there. he has even less range then jigglypuff did, and a worse recovery when he gets knocked out. he can't bait anything, all he can do is wait and wait and wait until hopefully the other player drops their controller and then he can get a few hits in before running away again.
there isn't even a problem with giving lucas a hitbox on his snake anyway so I don't see what the big deal is. Lucas could really use it so he doesn't get wrecked by those characters so badly. it's not like giving him a zair will suddenly make the matchup 70/30 in his favor, it'll just give him SOME WAY to fight back. as it is, there is nothing he can do against a character such as marth that can shut down any possible way he can approach with a forward air. giving him a disjointed aerial with some range will not break him, it will just make him competitive again.
if you disagree with that, you really just don't understand how lucas works. he's an aerial oriented character (why do you think he was given so much momentum?) that cannot approach through the air. if you want to main lucas, you have to bait your opponent, but you can't do that because he's all momentum. he's fun to play against people that don't know what they're doing, but if there was a national brawl+ tournament, I wouldn't expect any lucases anywhere near the top. his current weaknesses are too glaring for him to be a competitive character.
fixing his zair so it has a hitbox like every other character in the game won't break lucas or anything, it'll make him good again. people like matt are trying to use neko's ******** tradeoff system to give things lucas doesn't need in order to make him even more gimmicky then he already is. what he NEEDS is something as simple as a disjointed hitbox on his zair. that's it.
and yes, I know you can't currently add hitboxes. this is for the sake of the argument.