Okay, here it is:
Using a long focal length while shooting at an angle, usually gives photos an off look. So, either get lower at the level of the cat or use 24 mm at about the same angle. You'll see that the subject sticks out.
You have to consider what photos are. A photo is a bunch of shapes that the human eye has to see; for a good photo, the human also says "wow". For this, you need enough light to make those shapes clearly visible (sure, mood photos may differ). However, this is not enough. You also need to see differences among shapes, and this requires dynamic range. You have to fill a lot of more of the eye's dynamic range to make the subject pop.
What the cat photo lacks (and the flower shot as well) is dynamic range (aside brightness). Basically, everything is murky, it's difficult to perceive where one shape ends and another starts.
Because the original scene has a very low dynamic range, you can improve it through exposure only to a limited degree. However, you can improve it more in post processing, by increasing for example the Whites (in LR4).