For those that don't know it, LR Develop module uses a wide-gamut color space very close to the ProPhoto RGB color space - Melissa RGB.
The LR color space was named after one of the LR development team members - Melissa Gaul.
We can't change the working color space of LR.
I'm not sure I'm following you on this. You do choose the "process version" in LR which dictates how the raw data is represented in LR. And I use XRite to create my own profiles, which also affect color rendering. What we work on in LR are proxies, created for our screens to approximate what the output will look like. It's not until we output (print or export, for instance) that the raw image data is rendered into the final color space and resolution. Unless I'm missing something (entirely possible).
The process version is the set of algorithms that determines what Develop sliders are available plus how and how much those sliders change a photo.
Adobe Photoshop Lightroom 4 * Process versions
The working color space in LR has always been Melissa RGB.
The key point is Adobe designed LR so we use a wide-gamut color space to view the interpolated colors of Raw files.
Raw files have no color space, which means the sRGB or Adobe RGB 98 settings in the camera
have no effect on Raw files.
Adobe and other image editing experts recommend using a wide-gamut color space for editing, and once a photo is edited then choosing the appropriate color space for the use of the photo.
As unpopular mentions, few people have electronic display devices that can display an appreciable % of the Adobe RGB 98 color space colors not included in sRGB.
When it comes down to tablets and other mobile display devices the color temperature of ambient light falling on the display becomes a factor.
Dumbing it down to a lowest common denominator certainly is appropriate for the casual hobby photographer that relies almost entirely on sharing photos electronically.
As CameraClicker alludes to, it benefits a professional photographer, and the photographers clients, if the photographer has a good grasp of color management fundamentals.