Lucian almost single handedly strangles the bot lane meta. Immobile carries not named Jhin get destroyed by him in lane. He is safe from tanks and assassin's in the mid game thanks to mobility and a long range ult if he gets zoned. But surely he pays for it in late game damage? Well yeah he will deal less than Jinx or Cait when they can make use of their conditional strength but he is still a crit carry and does comparable if not superior damage than other crit champs at 6 items. He has everything and pays for none of it. Even his range doesn't hurt him much. Many jumps are about 600 range and many skills are 800+ range so in theory if lucian can be jumped on so can Jinx or MF but at least lucian can dash away. As it stands not picking lucian is to play sub optimally and picking immobile scaling champs is to actively handicap yourself. Some champs got far more from the adc update than others and some even got shafted.
Also I hate when people say "its cause he is fun." If lucian is at 35% play rate because he is so much fun than he should have been the most play champ since his release even when he was weak. People like him cause he is strong has agency in the game. He is " Its like how every said Riven was popular because she was fun then everyone jumped ship to fiora when she became strong, AND I LIKE RIVEN. Champs can have a large player base that supports them and keeps their play rate up. Jinx barely falls below 10% Riven has a lot of mains and lucian DOES has a large player base but it is not 1/3 of bot players.