Personally, I just want him to gain some sort of identity.
As of right now, Lucian suffers from being outclassed by every other ADC. When he was released, he was unique; he was THE ADC to pick for pure damage and 1v1 kiting. But people complained about it and eventually Lucian got nerfed to the point where he doesn't have any unique abilities going for him.
His passive, Lightslinger, is not in a bad spot. Just kinda weak in the early game. If anything, I think his second shot should deal 100% of his AD to minions. There are so many times when I'm trying to push a wave and I miss one CS just because my second shot wasn't strong enough to kill the creep.
His Q is alright, but there's nothing unique to it and it's buggy to where it can be dodged even if the ADC doesn't really try to avoid it, causing Lucian to lose the trade.
His W is, in my opinion, really bad. It used to be pretty good when it had it's AD ratio and when Lucian used to have his 550 range. Now it's really lackluster. The ability is easily avoided and the animation is really slow; by the time you hit someone with it, they're already in range to kick Lucian's butt.
His dash is by far the weakest dash in the game right now. It used to get rid of slows, which was pretty overpowered, and it used to have such a low cd that he was unreachable. But now, it's literally just a dash. Nothing else. You can argue that the CD reduction with Lightslinger is unique to him. But Graves's dash also has a CD reduction mechanic; with each autoattack, he reduces the CD of his dash by 1 second. Not only that but his dash gives him extra attack speed, a mechanic that every ADC wants. Lucian's dash deserves to have some unique trait that gives Lucian an edge in an area of expertise.
His ult used to be pretty good back when it had a lower cooldown. It wasn't 100% reliable, but it could be used for a variety of different things. Tower poking, waveclear, damage, executing lower health enemies were all good uses of this jack of all trades ultimate. Since the CD increase, his ult's use has severely diminished. You could use it for waveclear, but for the next two minutes your ass is grass. His CD gets lower as you level it; but his ultimate scales really badly into the late game. Sure that 2500 damage is pretty awesome when you use it on a squishy; but the fighter is just going to laugh at you when your ultimate just does a measly 900 even if you bought a Last Whisper and a Youmu's.
I just think that Lucian needs some changes to his kit to where he can be an ADC instead of a pseudo-assassin. Give him some sustained damage options. I'll probably revisit the thread if it gains enough attention to voice my thoughts.