Have you visited any of these RL companies in SL?
I've visited the American Apparel store and one of the car sims. Clearly, the car sim was not successful since I don't even remember the name of the car or the maker. As for AA, I was familiar with them before, so I didn't really come away with anything. I might wear their clothes IRL, but my clothes in SL are pretty much whatever I can mash together. I visited them cause they were at the front of the line in building their store.
Now maybe if someone started making RL versions of Silent Sparrow clothes . . .?
People are certainly making money off RL companies coming to SL (if those prices are to be belived). The RL companies are also adding much needed capital to Linden Labs. But I haven't seen any company really ADD anything to SL that enriches MY experience yet. So far, that's all done by us pleebs.
I feel like SL is the web circa 1997 or 98 - when you'd wonder if the counter at the bottom of the webpage was just corporate employees visiting, cause there was nothing to see there.
Did RL companies ruin the web? They certainly changed it and took over some of the little guy's work. But, the content I spend the most time looking at (web wise) is still produced by the little guys. Blogs, Flickr, Youtube . . . that's not content produced by Yahoo or Google, even if they host the sites.
I predict that user driven content will continue to drive SL. Maybe I'll be wrong and we'll all be working for Microsoft or Acme Products R Us.