It is all about locking in the user...
Into something they can't do without, usually in more ways than one.
Microsoft (presently) has the dominant operating system, but they also have the dominant word processor, browser, and spreadsheet as well. All of these lock into each other. Then they come out with an improved version (take your pick which one it is) and then people start using it. The items they pass among themselves require others to do the same upgrade, just to stay "with the program" and use the data passed. And so it goes. A vicious circle of upgrades.
Google is attempting to break the cycle. Good for them! If they succeed in interjecting themselves in one of the paths, they they can move the users over to their "circle of upgrade". They need to convince people that browsing with Chrome is a "better" experience (it may well be, I haven't tried it). Then slowly the web applications will need to address the market since they will insist on it. Oh, well there goes the Active-X pages, and their lock. After this everyone will benefit as we won't be fixed in Microsoft's version of the "upgrade loop". The problem is that we will (eventually) get into Google's version.
The determination of "good"/"evil" is left to the future.