Probably because Vivian and William couldn't stand each other, according to rumors.
I read that there were discussion, but Viv and Bill knew that it wouldn't work and were happy playing supporting characters to Lucy. They were smart. A Fred and Ethel show wouldn't have worked, even though I would have loved a Mrs. Trumble spin off.
The Carolyn Appleby show is now in development as a back door pilot on NBC.
Spinning off supporting characters from a sitcom rarely works (yes, I know about Rhoda, but even that didn't last long). See: Phyllis; The Ropers.
They tried to and offered Vivian and William a huge amount of money for that time to do it. William wanted to do it but Vivian hated his guts and flatly declined it.
Lucille Ball was going to do it, but Gary Morton talked her out of it.
r7, dear one, that would have been impossible, since she was still very much married to Desi at the time.
Because Fred moved to "My Three Sons" and Ethel had had enough of it.
[quote]The Carolyn Appleby show is now in development as a back door pilot on NBC.
Word on the street is that Carolyn loves it in the back door.
Marian Strong, still trying to lay that egg
R2 is right, they could not get along. But also at the time, I don't think many people recognized how deft a comedic actress Vivan Vance was. She was often given the funniest lines in ILL an always pulled them off. Lucille Ball had so much attention and adoration that she threw the other three talents in the shade.
Vivian Vance made the first two seasons of The Lucy Show bearable. She was always amazing when she was fighting with Lucy.
They saw how "Mrs Trumbull Presents" went down the tubes.
The Marian Strong spin-off "Cackle, Cackle, Cackle" also never got off the ground.
VIvian and William fought over where the new sitcom would take place:
Albuquerque or Steubenville, OH.
Ethel proposed an alternate series idea where she was a merry widow out on the town after Fred's death, but it didn't fly.
The other factor was Desi Arnaz. He produced the first year of The Lucy Show and it was by far the best season. Some episodes rank up there with I Love Lucy.
Once Vivian Vance left, things really went down hill.
A spinoff was presented but Vivian and Bill hated each other at a level that was psychotic. When she did The Lucy Show, Bill would throw shit at the studio door when they were recording. My Three Sons shot next door. This is on the Lucy Show DVDs. When Viv heard that Bill died, she said let's celebrate with a round of drinks. Bill was a drunk, a gambler, and never knew his lines. He would ask to only have a few pages of dialogue so he could leave to go to the track. He moaned all the time. Viv referred to him as the old man, and was insulted that they paired her with someone who was so much older that herself.