He needs to be a better player.
I don't care about stats you put up. He was on a losing team, in an offense designed to get him the ball. For the same reason Austin Hooper wasn't a good tight end, even though he put up monster numbers in Atlanta, Calvin Ridley isn't automatically a stud receiver because of the numbers he put up.
Is Juju a dominant, stud #1 receiver because of his 2018 season? Or is he a pedestrian third receiver because of what he did this year? I'd contend that he is the player he is--a reliable target in the middle of the field without any explosive, game-breaking potential. A big-slot type player. He's closer to Tyler Boyd than he is to replacing Pittsburgh Antonio Brown. When you can evaluate a player, the stats they accumulate are more noise than anything else.
I have Ridley closer to a... Robert Woods, DJ Moore sort of tier than I do to Nuk, Adams, Thomas, Hill, etc. Good piece, not an alpha #1 WR in the NFL.
If you differ with me, that's fine. But that's where I'm coming from. I'd easily take someone like DK Metcalf over him. I prefer Golladay over him. I have CeeDee Lamb close to him, but slightly ahead. If there's no injury questions, I'm taking Courtland Sutton over him.
If you're saying a #1 means one of the 32 best receivers in the league, then he fits that description. I am not using that description. I think there's probably less than 15 of the sort of player I'm describing as a true #1 guy--someone capable of dominating a matchup on a play-by-play basis, regardless of situation.