So, OldRoy, I use Lightroom 4 at work in the same way you want to use it -- that is, as a raw processor only, not as a database. Here's what I do:
I have a carefully constructed file system, with raw files from individual assignments placed in folders. These folders are then opened in Photo Mechanic so I can do the basic editing and metadata - renaming, full captions, and keywords. PM is the fastest browser out there, and its ability to create extensive presets for metadata, as well as the Structured Keywords panel, help greatly speed up my workflow. Once I have added the metadata, I use PM to select the images I want to process.
Then I use Lightroom as my external editor. Simply selecting the photos I want to process in PM, and choosing the Edit command, opens Lightroom to the Import dialog, where I Import the photos into Lightroom. Then I do whatever raw edits need to be made, and then Export the final images as TIFF or JPEG files.
The original folder of raw files is then moved to my server. This of course breaks the connection to Lightroom, but as I am not using the archiving capabilities, this does not bother me. (Yes, I am doing it "wrong." So what.)
So why use Lightroom when I can get the same raw processing capabilities in Camera Raw? Simple - Lightroom offers far more in the way of presets for raw processing and Exporting than CR does. So it's another way to speed up my workflow. When I'm shooting 700+ assignments a year, and processing out 10K+ files for our office, anything I can do to speed up the post production is most welcome.
At home, I use the full capabilities of Lightroom for my personal and freelance work. But I have far fewer images, and they are all on one computer (no server, no laptop), which makes it easier.
Hope this helps.