In a Standard format like the one that the Khans of Tarkir block created, one with a decent amount of very good planeswalkers, it surprised me to only see Despise get some Khans block play, and really very little play in Standard.
The designation of planeswalker is, of course, quite interesting. At the time it was first released, it was quite relevant with Koth of the Hammer, Tezzeret, Agent of Bolas and Venser, the Sojourner running rampant. Now there are plenty more planeswalkers to deal with in Standard, such as two incarnations of Ajani, Ashiok, Nightmare Weaver, Elspeth, Sun's Champion, Kiora, the Crashing Wave, Sorin, Solemn Visitor and many more. Despise can obviously deal with planeswalkers. It's outclassed in Modern by a bevy of other discard spells, but in Standard it seems it should see plenty of play that it hasn't. It seems that Thoughtseize is getting the job done on its own.
Still, dig up all of the old New Phyrexia copies and Friday Night Magic promos. Despise is still back. When Thoughtseize leaves Standard after Theros block rotates from the format, it may once again see play with lots of strong planeswalkers still sticking around.