User blog comment:RoznosicielCiast/Least popular champions/@comment-5556439-20130130070527

The pimary reason alot of these underplayed champs arent played is because they dont mold with the current meta. Think about it, take Xerath, he has high cd's, medium damage early game, high mana costs, and easily cc'd before he hits level 6. He cannot dominate lane without jungle help and even if he does, he puts himself in great risk, not to mention mid's that are in almost every game like Katarina essentially shit on him because of his virtually non-existent mobility. Others like Viktor are just too awkward to play unless your familiar with them, and also, you dont see many players get high kills with them(which creates hype). The attractiveness of a champion essentially creates their viability it seems. Ezreal is a huge example of this, extremely fun to play, high risk high reward feel, his attribute of being an ADC, and his in general "candy" feel. Every one of the champs you listed besides Karma. Trundle, and Zilean dont really match well with the meta. They are either too awkward to lane, too easily countered, too easily shut down early on, or just bad right now.