The numbers you are describing make sense to me. I don't know much about PS Elements, but from a photoshop and colorimetry point of view it sounds like everything is working as it should.
Here's what's going on:
RGB and HSB numbers by themselves aren't enough to make any judgment about color or saturation. They are both device-dependent—you need to view those numbers as coordinates within a particular space. Without the space you can't make any generalization about a RGB or HSB triplet being 'pretty unsaturated'.
In your example you have an image that is in ProPhoto RGB—a huge space capable of colors so saturated they don't really exist. You also have RGB numbers that you are getting from your monitor via the screen color picker. The screen color picker should be showing you RGB values relative to your monitors space—a much smaller space that can't come close to the max saturation of ProPhotoRGB.
So if the screen color picker is showing you an RGB value of [255, 255, 0] that's going to be the most saturated yellow available in the screen's color space (Since I don't have your monitor profile, I'm going to assume your monitor acts like sRGB). It represents 100% saturation—the most saturated color your monitor can display. But the ProPhoto space can contain much more saturated yellows. In the Prophoto space this yellow might only represent 67% of the possible saturation. To get this same yellow in ProPhoto you would only need the RGB values [234, 251, 84]. It's the same color appearance, but it's well inside the boundary of the ProPhoto space.
If you only look at the numbers you might be led to believe that RGB [234, 251, 84] is less saturated than RGB [255, 255, 0], but once you interpret the numbers within the space you can see the ProPhotoRGB[234, 251, 84] and sRGB[255, 255, 0] represent the same color.
With this in mind everything else makes sense. Say you have an ProPhotoRGB file with that yellow value of [234, 251, 84]. To display it the computer looks at the numbers, converts them to your screen's profile space [255, 255, 0] (in our example) and sends them off. If you strip the profile, the system no longer knows how to interpret [234, 251, 84]—so it just sends the numbers off to the screen resulting in a much less saturated yellow. Because ScreenRGB[234, 251, 84] is less saturated than ScreenRGB[255, 255, 0].
This is also why the numbers change when you convert to sRGB—the numbers change in order to keep the appearance the same.