Google just offers a service. It offers it for free. Take it or leave it. As long as it’s good, people take it. If it gets bad, people leave it within seconds. People don’t depend on Google, they make themselves depending on it by not using another engine. They could switch to another engine within a couple of seconds, though. Other engines are currently directing so little traffic to StackOverflow because so little people are using them… not because SO is not in the search index of these. If more people were using them, they’d still find SO and the numbers for other search engines would rise. People just don’t see a reason for switching, since Google works nice for them.
This is different to Microsoft. Microsoft offers a product. An expensive one. If you decide to buy it, you cannot just switch to something else within a couple of seconds (exchanging Windows on your HD with Linux is far from being an easy process). Further you won’t get your money back if you switch, so you want to get the best for the money you paid, which means you must stick to the bought product until this product has finally paid of or you wasted a whole lot of money. Unlike people dependency to Google, that people can break up themselves by just typing another URL into their browser, the dependency on Microsoft (and their Windows) is much tighter, much harder to break, makes them feel much more like being caught in chains.
Despite that fact Microsoft’s political used to be pretty bad in the past. This has changed. Microsoft is far, far less evil today as it used to be. Some things they are doing today even seem reasonable to me and sound like good ideas… despite the fact that I still see gigantic deficits in Windows and MS is fighting really hard to get rid of them, each Windows editions taking them one step further to this goal… but it’s still a long road to go. Google on the other hand used to be the good guys and their image is just slowly fainting (their interpretation of privacy sometimes suck, they don’t always act as good as one would expect, etc.)
As always in live, good and bad are just to ideals and everyone swims between them. MS getting cleaner, Google getting dirtier, but there is still no reason to out onto the streets. If Google starts getting too evil, there is also no need to go out on the streets. People will just stop using Google and that’s it (not causing them any financial loss, as they never paid for it in the first place).
BTW, I think every search engine sucks. I search via allplus.com, a meta search. It will search Ask.com, Google.com, Yahoo.com, and Live.com (Microsoft), merge the results (recognizing the same page referenced by multiple results), categorize the results into clusters and show the results nicely sorted by average rating among the used search engines. Further it runs an image search, a blog search and a video search as well (if the used services offer such a search) and shows top results of these by the side. If you like, you can quickly switch to a full image/video/blog search.