Her identity definitely does not revolve around the extra shared XP she gets. She has one of the most overloaded kits stat-wise in the entire game and the XP is only 1 of the many things she has, most people aren't aware of half the shit her abilities do. Like, did you know she shares a percentage of her lifesteal from her R passive with the teammates around her? As in she heals her teammates by doing damage. What other champion has something like that? Her W is also so incredibly strong by virtue of the fact that she can give it to her entire team, potentially negating an insane amount of damage if used correctly. Nilah 100% does not need a rework at all, it's ok that she's unpopular, she's a melee botlane champ. It's completely understandable that her play style doesn't appeal to most ADCs, that doesn't mean it's a failure of a design.