use of trademarks
Of course the owner of a trademark would like to be the only one permitted to use that trademark.
But, that is not the way it is.
Trademarks are even used for comparison purposes in advertisements all the time.
We have all seen the drug advertisments that say their new drug is 30% more effective than placebo. (Placebo not being a trademark at all.) But, we have also seen advertisemens saying their drug is better than the competitors. And they often times mention the other product by trademark. The famous Apple ads certainly use the Microsoft trademark, right?
All search engines are doing is making it easier to find sources for trademark goods and goods competing with trademark goods. We generally do not have a means to search print and audio ads that way but in time that may be the case too.
Individual ads on google could violate the use of a trademark. But, that is hardly the search engines fault.
To be honest, allowing the use of trademarks in ads (even on search engines) is a valuable service to the consumer. Both those looking for trademark goods and for those looking for a cheaper alternative. Or, those who do not know what they want.
As for the timing of these law suits or the new Google policy you can speculate. But, the courts in time will need to figure out this ability of consumers to conduct searches based upon trademarks. And if you only allow the trademark owner to use the word, consumers do suffer.
Search engines should not be the exclusive use of trademark holders. Perhaps some other search service could provide that feature if they wanted to. And maybe some do. But a more broad use of trademarks is in the interest of consumers.