You'd be surprised at how many people still use Yahoo for search.
Google is buying a placement (they pay Mozilla and probably Apple). This really doesn't do much in the way of restricting the activities of other search players. Google is more likely to get themselves in trouble with the FCC over Google Voice.
Apple does not have the market share to matter. There are plenty of phones and Apple's share is tiny compared to someone like Nokia. Restricting the types of apps for a closed system hasn't got anyone in trouble yet, since you have to do a lot of logic leaps / market segmenting to get to a monopoly position for Apple. Heck, the iPod and iTunes are nowhere near monopolies.
Microsoft, in order to protect Internet Explorer (product A), charged higher prices on Windows (product B) to OEMs that wanted to include Netscape Navigator. This is an illegal tying of products. It is considered a restriction of trade. Given Microsoft's market share (and probably, sadly, Microsoft's at that time low contributions to political parties), this is major league anti-competitive behavior. Tying of unrelated products is the problem.
As a side note, I get that you are trying to prove a point with the logic "everyone does it, so it is fine", but I am neither fond of that particular phrase nor do I believe it is true for that matter.
Their bundling of IE with Windows, however "strategically right" it was, was also an abuse of monopoly power. And they were convicted of it.
"We are going to cut off their air supply. Everything they're selling, we're going to give away for free" - Paul Maritz
"We're giving away a pretty good browser as part of the operating system. How long can they survive selling it?" - Steve Ballmer
1) Why did the court consider motivations to be important in the US v Microsoft antitrust case? The body of law and precedent requires that it does, in this case. Though I am not a lawyer, a quick google search found a key phrase in Judge Jackson's Conclusions of Law document: "once it is proved that the defendant possesses monopoly power in a relevant market, liability for monopolization depends on a showing that the defendant used anticompetitive methods to achieve or maintain its position."
http://www.usdoj.gov/atr/cases/f218600/218633.htm
That last phrase "to achieve or maintain its position" may involve the consideration of motivations. Otherwise, a defendant might say "we weren't dumping our product; we were merely giving our customers more for less!" The discovery of telling quotations such as the two above would give lie to such a defense, and this is why the "cut off their air supply" quotation was considered so carefully during the proceeding. That document is very interesting to read. It discusses motivations in several places.
2) Why does it matter today, now that browsers are (for the most part, Opera and others excluded) free?
Well, I guess it's really the Consent Decree and the Rule of Law that makes it matter today. If the terms of your divorce say that you're not allowed to see your ex-wife's children, it doesn't matter if 8 years have passed and you have since stopped drinking. You must abide by the terms of the decree to avoid contempt of court.
I said "8 years" in the above example, because that decree became effective in 2001. It's interesting to note that there was a prior decree in 1995, and Microsoft did actually have to go through a contempt of court proceeding for not being in compliance with its terms:
Emphasis on "possible".
People like picking on MS because they believe in their heart of hearts that it was some evil on MS's part which led to IE becoming the dominant browser, but that is not so. At the crucial moment MS had the better browser (IE 4 vs. Netscape 4), I made the switch myself to IE when nobody else was using it because it was a better experience (I currently use chrome for the same reasons). At a time when Netscape was bloated, slow, unstable and had serious usability problems, IE was faster, more stable, and had a better UI. MS bundled their browser with their OS. And, even more importantly, Netscape went into a phase of directionless thrashing around. We know now that they rewrote their code base for NS 4 for no reason whatsoever. They continued to churn their code for several years with no noticeable improvements to the core browser functionality. People tend to forget that Netscape effectively died at the height of the browser wars. They screwed up so bad that they dumped the browser on the open source community, which spent several years cleaning up the code until it finally turned into a decent browser.
But by then Netscape's failure and MS's success had already cemented IE as the dominant browser, at the time.
But despite IE's bundling there is today again a healthy competition amongst browsers. Firefox has a sizable marketshare with chrome, safari, opera and others as viable alternatives. Solid proof that with a better browser it's possible to compete against bundled browsers.
The interesting thing about the browser wars is it's one of the few occasions when history was written by the vanquished.