Why was this cancel

Because it sucked and people bailed.

Apparently needed more room for CRAPPY reality programming. Not the best of shows but I looked forward to it each week. Can't say that about many of the Major Network programs. I reserve that for much of what is on FX.

The show was canceled bc people stopped watching and the viewership was too low to justify investing in more seasons

It was cancelled because NBC has continued to suck since it's fall from the top in the early 00's.

I think if they did this in 13 episode seasons it would have worked.
The stories were good, but there were too many filler episodes.
It got too long in the story telling without moving it forward.
26 episodes would have been plenty to tell what they told.
Then maybe they would have enough cash to do a movie to finish it.