The title says it all really. Why would I want them and how do they differ from regular spawners.

 

They have a purple lore below the "monster spawner" name. It says the mob's name which it would spawn. "Skeleton Spawner"

 

If you place them they turn into a pig spawner and lose a bit of their value.

 

So why do they cost more than standard spawners. It simply because of the purple lore?

 

because they were past spawners that were the ones on mob name that could be silk touched and then get the lore,the thing was removed
(i got that info from someone i forgot)

 

Pretty much from yoshi, they were once used to be silked once placed.

Since your question is thoroughly answered, I'm gonna go ahead and wrap this up. If you have more questions, feel free to PM me