Business and trademarks

A couple of days back I was discussing about Google with friends when one of them mentioned that Google has become such a well known brand that it has entered into Merriam-Webster dictionary as a word. I told them this is actually not a good thing for a brand. They didn't believe what I was saying. Having done a trademarks course I know a thing or two about it and explained it thus:
Google has created a unique product for search which is widely acknowledged as the best online search engine. It has a unique advantage over competitors now. Anyone wanting to search online would first think of Google search. This is because the brand differentiates it from competitors such as Yahoo or MSN. Users are well aware of it and so they prefer Google search over other engines. But if it becomes a generic dictionary word then it lose its value as people would start using the term Google or worse 'googling' for online search. It wouldn't matter to users then which engine they use. Google for them would mean online search. The differentiating factor that was Google's brand then lose its advantage. One could as well go to Yahoo search and say he is googling.
In the history of brands there has been many a cases where companies lose their valued trademarks because they become generic nouns. It is for this reason that companies tend to use their trademark always as an adjective. Google search, for example. It is almost always followed by a noun. It is for this reason that Google wouldn't be amused if someone tries to make a word 'googling'. Companies protect their marks for the fear of it becoming generic, sometimes even launching PR campaigns.
Some brand owners didn't protect their marks well enough and they have become generic nouns and some are almost on the verge of becoming one.
Some examples of tradmarks that became generic and hence lost the advantage over other products are:

Aspirin: The product name became generic noun and now companies use it just as synonym for a particular medicine.
Escalator: Was a brand, now a generic English word.
386 : This was Intel vs AMD case which Intel lost and also lost the advantage of brand 386.

Some trademarks on the verge of becoming generic are:
Kleenex : Tissue paper.
Xerox : People have begun using Xerox word as a generic word for photocopy. Xerox is fighting to prevent its term from becoming generic by launching PR campaigns.