Trouble is Edwin, if companies were allowed to protect rights in the way you suggest, it would lead to price fixing and companies who are not open to keyword competition running a type of monopoly.
I can name many companies that operate in this way, one example... HPI
Check out the google ads for car data checks when you type in hpi.... there are none because HPI shut then down via google. How many competitors on page one of google, a grand total of 1.
Result hpi selling car data checks for £19.99 when it costs them less than £1.50 to perform a check, price fixing by the big guys. They use the Autotrader brand to compete on price, but HPI keeps that brand to get the creme from google.
I think there is also a vast difference between an existing, trading business registering a domain name and a domain investor/speculator/whatever (delete as appropriate) doing so. EVEN IF IT'S THE SAME DOMAIN!
Not that clear cut either
http://en.wikipedia.org/wiki/Genericized_trademark
A few examples of trademarks which have lost their legal protection in the US are:
* Aspirin, originally a trademark of Bayer AG
* Escalator, originally a trademark of Otis Elevator Company[4][5][6]
* Thermos, originally a trademark of Thermos GmbH
* Yo-yo, originally a trademark of Duncan Yo-Yo Company
* Zipper, originally a trademark of B.F. Goodrich[7][6]
* Kerosene, originally a trademark of Abraham Gesner
* Butterscotch, originally a trademark of Parkinsons
* Heroin, originally a trademark of Bayer
* Sellotape
* Walkman
* Pop Tart
* Hoover
* Zeppelin
* Biro ballpoint pen
* Tipp-Ex, originally a trademark of German manufacturers Tipp-Ex GmbH & Co. KG
* Pogo for the toy Pogo stick[8][6]
* Gunk[8]
* Phillips screwdriver and screw