This is a show about people with superpowers. The chief villain has to be powerful in order for the superheroes heroism to mean something.
Bingo. It was great to see the Petrelli boys going up against Sylar with only lame-ass flying powers at their disposal - and a clever game plan that ended up working, despite the overwhelming odds against them. They beat Sylar with their smarts, not with CGI. That is what I want from this show.
Why are the same writers who do so well with Peter suddenly stupid with Grey?
They
don't do that well with Peter - it's been hit or miss. The premise for the character is good. The actor, while not magnificently talented, is very well suited to the role and also cute. That goes a long ways with me.

So sue me. They've written him as a dolt and then turned around and given him unexpectedly clever things to do. Peter has been dragged all over the place just like all these other poor characters, but he hasn't been abused as badly as Nathan, Mohinder and Sylar, to cite the most egregious cases.
Samson is just boring - what's the point of the character? We expect Sylar's dad to be a psycho so the cleverer thing to do is to make him a saint. That would throw Sylar for a loop -
now what's his excuse for being nuts?
Cure his cancer and have him as just a psycho with TK (no other powers) and Samson would rock as a villain on this show.
Eh, he's just Sylar except old and wrinky rather than young and hawt. Not an improvement!

Poor John Glover deserves a more interesting role than just to be Old Geezer Sylar.
What's really happening here (and forgive me Temis but I think you're demonstrating this quite clearly) is that, most likely due to fan (and therefore studio) pressure, they are currently stuck having to work with Sylar's cult of personality.
If I had some amazing mind control powers over the writers, things would be very different on this show (and very disturbing

). And I wouldn't necessarily even keep Sylar around. The problem with this show is that the single most interesting element they've come up with is Sylar - and they've tried a million other things, plot twists and new characters, and for the most part, it hasn't worked. Which leads me to believe that Sylar was a fluke, which means if they kill him and try to replace him, odds are the results will be inferior.
There's a reason that the formulaic 24 (which I love) is still so popular. No one tries to pretend that it's anything other than what it is: The Jack Bauer Power Hour.
Wait - are you arguing that
Heroes should be
The Sylar Power Hour, then? After all,
24 keeps chugging along, long after they've run out of new things to do, and the viewers keep watching, so is originality really all that much in demand anyway?