She is in a decent spot. Thing is just meta stuff alongside with her not having the most damage and interractive kit.
There once were in early S6 where ADCs ruled the meta, Liss was top priority because of her point and click stun
Meta has shifted into a more tanky meta, so champions like Orianna and Syndra that can harass with decently low cooldown with some distance away are generally just better. That's just how it works.
Balance stuff, something gets nerfed leaving other stuff stronger and suddenly some champ gets OP.
Tristana was actually also left behind for almost a season until crit items got hyperbuffed and some other ADCs nerfed leaving Trist in a way better spot in comparison.
Thresh has become meta (due to indirect nerf to mage supports with dorans shield start on ADCs), really forcing Kalista into meta again also after her buffs of course. Her W synergy with Thresh's ranged autoattacks and with him being a tank to have synergy with her ult.
Liss will definetely see play again, it's just a question when. No rework needed in my opinion