Varus was considered a "shit" and "unrealible" immobility ADC, resulting him in having such a low pickrates. Now he's seen loads of spotlight as a mid laner, you want to take that away & put him in the shadows again??
Differences between Varus & champions you mentioned:
Her Q has the same standard damage when she pokes through minions to the enemy champ, while Varus's Q will have reduced damage to each enemy unit it passes, plus the fact it takes time to ramp up the damage, making him vulnerable at that point. Liss has E to escape from danger, while all Varus does is run with his two feet & needlessly burned ult.
She was picked as a Supportive Top laner, only to help assisting more on her team's mid & ADC laner. Not so much of a kill-champ, only knows how to be an annoying female Teemo(so-so~). Varus, well, just does damage & that's it.
She was a rare pick as a top laner due to her immobility, but her new Q can help her get away from sticky situations better than Varus does. Her QEEWEEEEEEQEEE combo could be really annoying & hurts a lot especially when it comes to fighting against melee champs.
Additionally, why are you so enforced in having champions to be fixed at their original lane just because their Attribute says so?
Marksman/Assassin. Played top lane instead of bot.
Mage/- Played as support.
Fighter/Marksman. Played as mid lane.
Assassin/Fighter. Can be played as a tank jungler.
What about these above? Where are all the arguments about these champs go, especially Teemo?
EDIT: I love how OP doesn't reply this thread as he still stubbornly spits "Varus shud be ADC, not mid" rubbish everywhere. He was useless in the Assassin meta, now at least he gets some spotlight in the Tank Meta, is that so bad? Don't try to be a meta-sheep plz.