Because do you really think those samples are properly exposed? A great camera cannot compensate for poor photography.Instead of bashing could you please keep your mouth shut. I tried to be polite before but I am losing my temper. Or t least think before you type. I don't have the right to have a dark underexposed looking image? The shadows should be clean in such situation. I didn't want criticism regarding my images or my technique I just wanted to figure out the noise issue.
Dude, you really take a bit of critics personal, don't you?
You have to prepare for critics if you upload your images to a website - it's always the same. It's web 2.0 - share your opinion on everything, even if no one would be interested in your opinion, you still share it don't you?
So just let the critics talk as well, since we also let you talk.
That said, I'll talk now.
After taking a look at your pictures, I suppose you want to create a dreamy look on your photos. However, focus on the flower photo is badly set, also is the exposure. Why did you take it at 1/2000sec at aperture 2.8? Where is the point in this?
Seriously, I have to defend Canon on this: take a look at that black. A camera is not supposed to fix your incorrect exposure! If you need dark images like this one, it would probably work out better if you take shots in RAW and afterwards adjust brightness.
I think that your banding would then be reduced by an awful lot.
Also imho the second shot doesn't look as bad as the first one regarding the banding and noise. I would guess it's because that shot isn't quite as under-exposed as the first one.
Just a suggestion:
People should sometimes practice more before complaining. Cameras don't fix pictures, they just take them.