NBC (ended 2010)
Simply because the writers didn't know how to use the characters. Let me break it down
Peter- Constantly powered him down by having his memory erased, taking his powers away, and giving him a new limited power. Peter had potential to be the best hero out of all of them, but the writers screwed that up. Also making him go through serious emotional changes during the volume 5 wasn't a good move too. I only say that because by that time his character should have been well developed.
Nathan- Too caught up in politics. Nathan was one of my favorite characters but his character was made pretty useless because he was constantly caught up in politics that provide almost no point to the plot. Except in "Fugitives" when he actually did something. But the writers screwed up with that by making the other characters forgive him too quickly. And just when his character was going to change, they killed him off.
Hiro- This one is a no brainer. His character was cool, but the writers made him useless. Constantly sending him off on mini missions that have a zero percent contribution to the story. Constantly ignoring his usefulness of his powers. Powering him down only to have him come back in the finale of every season. Just when he comes back you think he is going to do something important, but he never does. Then for the next volume they send him away on another mini mission. It is such a repetitive process.
Claire- One word, annoying. We can all agree that Claire was the most annoying character. Simply because every season she is always whining and complaining about something. She causes her own problems and drags others with her. She doesn't solve her own caused problems and instead relies on others to do it for her. She is a brat who constantly fails to understand what Noah has done for her even though in every season and volume Noah explains it. The writers tried to develop her character but they failed. After five volumes she is still the same Claire.
Sylar- I like Sylar especially during the earlier volumes but they pretty much did the same thing to him as Peter. The writers powered him down too much. They kept getting rid of Sylar and his powers, only to have him come back. Three times they did this. First the virus, next Angela manipulated him to work for her and Arthur. Finally he lost his memories and his powers once again. The writers wasted Sylar's character countless amount of times. I was disappointed that the show had to end though because Sylar looked like he was going somewhere in the end of volume 5
Nikki/Tracey/Whoever the hell she would be- I liked her as Nikki because it was simple. But then when they had the guts to kill her off, they brought her back just to keep the actress. I do not like it when they do that unless their is a proper story to it like the Sylar to Nathan one actually made sense and was pretty well done.
That is pretty much about it. The only two main characters I believed they used right were Matt and Noah.
I think that heroes fails BIG when throwing us in the face a lot of plotholes, stupid character decisions, powers mistakes or directly forgotting powers and continuity errors (most of them related to the "in the past" episodes or Hiro going back and forth in time)
Also, Sylar should have remained dead, or directly powerless (Sylar was unbeatable from the start of season 3 till the end) after the end of season 1.
On season 3, they drop an amount of villains with their own story enough for two seasons and they spend them on... less than one, just because "Sylar have to be the main villain"!
I get particullarly annoyed when Sylar explodes as a nuclear bomb and Claire survives as normal... C'mon, I know she have regeneration, but, regeneration from a NUCLEAR BOMB! That should have to be directly Atomic Regeneration. And, of course, killing the good villains (Bob, Adam, the guy from the government) and leaving SYLAR... stupid. And not to talk about the government professional soldiers being only a mockery in front of no trained people who only can shoot... ehhh, water.
So, heroes, to me, fails all on the story, cast was allright, background was good, hell, even the story was good until the end of season one, so, story decisions are the place where Heroes fails.
Without sounding too negative, I think some of the flaws might have been built in back in the pilot. I remember loving the first season but being surprised about halfway through that Peter didn't just mimic nearby powers, but take them on permanently. I was thinking you're kidding right? He's going to get exponentially more powerful as the seasons progresses until he's completely unstoppable and make every other character redundant.And on a TV budget, how do you solve every problem he's faced with the way he should? That's a doomed idea from the start.
Hiro was almost as bad. You can't give a character complete control of time like that without balancing it out...in fact I think they made Hiro a bit silly and naive as a *way* of balancing it out, but that's a bit doomed too because then you just dislike the character for being such a moron.
Sylar should have been in the same catagory, yet I thought it worked because he would always be alone, because he'd be one man with ten powers versus ten people with one. One of the best parts of the first season was watching all these characters work their way toward each other, knowing their strength would come when they came together.On the other hand that only really flies for one season. He should have died there.
So yeah, things went bad in so many places, but there were issues from the start...although had they stuck with the new cast every season plan, that wouldn't have been a problem.
I agree that keeping Sylar alive was the beginning end of Heroes. That was the end of volume one. It seemed like many people like Sylar so the kept the character and killed the story of Heroes. They added more characters then got rid of them. There should have been a world of Hero characters that fought against the villains and ultimately came together to find out their origin and battle the company and it's villains and destroying them all. But wait there are more villains in the world. They should just make a live character stick to the comics, for the most part X-Men tv show. Origins to future X-Men.
Well I can't really say much that hasn't already been said, but the first thing that had me say "wtf?" was when peter left his Irish girlfriend in a future alternate reality and he doesn't really seem to give her another thought.
I really did like the show when it was on and even though I knew the plot was getting ridiculous I still never missed an episode. I wish they would finish the story at least. How about one final episode where they can't stop the world from blowing up? At least that's an ending!