As lovely as the dresses you've linked too are, they're too ostentatious for the job required. Sure, some would be great for the evening, but for a walkabout, not suitable, and why she opts for lots of dress coats.
And silly I know, particularly given the press (and us) scrutinises her wardrobe and how much it costs but the items she does wear, probably represent more value for money. They're stylish and instantly forgettable and can probably be altered at some point in the future and used again.
I think she's caught between a rock and a hard place tbh with her wardrobe. Her natural style is incredibly Sloaney and while it would be great if she dressed a little bit more edgily, it's just not her, and not suitable unless she's doing something for the British Fashion Council, although SamCam has that niche sewn up.
Given her role, I think she dresses in exactly the way she should. Remember, she's still very new at this so give her some time. Look at Prince Edward's wife, she used to look a fright but is now very stylish. (I can't believe I wrote that!) Additionally, Lady Helen Taylor always looks great and in my opinion is the best dressed British royal, so hopefully she might be a reference point.
She has long. very public life ahead of her and am sure she'll figure it out as she goes along. And with any luck, she'll sort her hair out. It's lovely but it's dragging her face down. I think if she cut it even by an inch or too, she'll automatically look a tiny bit more modern.