2--No cass wasn't unique. The Q poke play style was something shared by all the above champs I mentioned and then some. Sure Xerath might so it in a straight line, Ziggs use a bouncing bomb while Syndra like Cass used a targeted circle of damage to hit their opponents. This wasn't unique and trying to pass it off as if it was is willfull stupidity. New Cass is truly unique. No other AP champ has the scaling of cass, nor the ability to put out constant damage like cass. It still needs some tweeking but it truly is something unique in this game.
I love how you just mention Q poke, because that's her entire kit, right? Talk about willful stupidity. What about her area denial Miasma (when it actually hurt)? It expands, grants vision, and slows. She had her twin fang too, which was unique, a spammable almost auto attack on a mage, and here's the thing: Both styles were viable. Her poison wasn't simply a setup for her one damage move, it was a powerful attack on its own, which could be further punished if the enemy was too close. That was unique. Having more than one viable style is getting more and more unique these days with riot stomping out anything other than one play style per champ.
I'll give you one thing though, new Cass certainly is unique. No other champ has such a horribly designed, unfun, unfitting passive that completely destroys the point of the champ. New Cass is a confusing blend of wanting to be a pseudo ADC mage with a half ass Veigar mechanic, and poison which does hardly anything at all.