The real problem with Cell is that he really has no backstory or motive, so it's hard to write an actual story with him.
With Frieza you have his empire, his background with the Saiyans, how he met Beerus in the past, his father, underlings, etc. There's more you can do with Frieza's character. Cell is literally just an Android created to kill Goku. He doesn't have any history with anyone, or any allies, or really any motive to do anything since he doesn't need to absorb the Androids anymore. Bringing him back just to fight Goku and die again would kind of degrade the character. And if you didn't kill him off, I'm really not sure what he would do since he doesn't have an empire to run or anything.