Life on Mars : Why did they make only 2 seasons of LoM?

I loved this series. What happened? It was popular; so, I don't understand the reason they pulled the plug on it.

Presumably the writers felt that they had done all they could with the series and wanted to go out on a high before they jumped the shark.

Life on Mars had a definite end to Sam's story, there was no need to continue on after it was clear he was Dead - not mad or actually a time traveller

Fawlty Towers pulled a similar trick.

Ashes to Ashes did a clever thing of moving the action to the 1980's with a strong female partnering Gene to give a twist on the character. I think that did go on one series too long though.

They should have skipped 2 series of ashes. It sucked

John Simm didn't want to do a 3rd series because this meant being away from his family, which was in London, I believe, while this was filmed in Manchester.

The reason for Ashes to Ashes is the writers weren't done with Gene Hunt, yet, & wanted to finish his story.