I got the idea from the Eureka drama, which reminded me of the Farscape drama.
Well, again, that "drama" is precisely the point. Naturally if a show is good and runs long enough to win a loyal following, then the fans are going to feel it was cancelled too soon no matter when it gets cancelled (unless it runs so long that it goes downhill/jumps the shark/etc.). Most of the shows that
really get cancelled quickly never win much of a following, except for the few that are really good like
Firefly. You won't hear many people saying that, oh,
Alcatraz was cancelled too soon, because it wasn't that good to begin with.
So the whole "cancelled too soon" perception isn't really about duration, but about quality. Every show ends eventually, and very few shows are successful enough to run as much as 4-5 seasons, let alone longer. But the better ones are missed more.
Although its true W13 ran longer than FlashForward or Firefly on the major networks, that's not a fair comparison. With its 20 season 4 eps that gives 58 total for the series, vs 94 by the end of season 4 for ST Voyager...
Why are you referring to
Warehouse 13 in the past tense? It's still on the air -- the second half of season 4 premieres next month. It hasn't been renewed for a 5th season yet, but it certainly hasn't been cancelled. True,
the ratings for the first half-season were down from season 3, but the renewal/cancellation decision won't be made until the network sees how the next block of episodes performs. One article's pessimistic speculation does not a fact make.
As for the number of episodes, numbers don't always tell the whole story. Shows with long seasons -- especially as long as 26 episodes, a figure that the Trek shows stuck with well after the rest of network TV had slimmed down to 22 per season -- need to pad things out with "filler" episodes, or settle for filming mediocre scripts because they have a quota to fill. Shows with shorter seasons need to distill things to the essentials, pack the story arcs more tightly, etc. So you're not necessarily getting a smaller amount of worthwhile content just because there's a smaller number of episodes.