I think Apple should be thinking more about customer satisfaction rather than rivalry with Google. Microsoft is also an enemy and using their search engine is no better than using Google's, in that point of view.
Regular people don't actually care. As much as this may be a moderate-sized thing corporately-speaking, it means very little for end-users.
Firstly, there are two types of people: those who care deeply about which search engine is the default, and those who don't.
Those who don't, won't give a crap. And in spite of the discussions on these forums, the people on this site are not representative of average users. Average users do not debate Bing vs Google. And sitting there and explaining to them all the thousands of reasons why Google is better (in your individual preference) than Bing won't mean a great deal when it's based on
your priorities, and particularly if they don't understand, or care about, the technical minutiae.
I mean, I absolutely
guarantee you that there will be a certain segment of users who prefer Bing purely and solely because it has pretty pictures in the background, and they really can't tell any difference in the search results. And they don't care if it's by Microsoft, cos they "type their files in Microsoft at work" (ie: not getting the distinction between Microsoft and Office). It may be earth-shaking for the techno-geek crowd, but ask your grandmother if she's hot and bothered about it. All they want is: type words, get sites. I use Google every time. But most people just want a search box, and as long as Bing generates results, a lot of people won't care or be any less satisfied than with Google. I really don't see how "customer satisfaction" will be impacted here, aside from.....
.... those who do, for whom Google won't be going away. There's no freaking way. It'd be like removing POP access from iPhone Mail, or HTTPS from MobileSafari. You're only something like 3 taps away from changing it back. I mean, what, are you just going to not buy an iPhone simply because Bing is the default search engine? That's like the definition of cutting off your nose to spite your face. For the want of 3 taps, are people going to refuse to buy an iPhone? Did anyone refuse to buy a Mac simply because IE for Mac was the default back in the day? Change it - who cares? Was customer satisfaction diminished because IE for Mac was the default rather than Netscape? (My own personal vendetta and struggle to finally banish IE 5.2.3 from my company's network once and for all notwithstanding.)
Secondly, it amounts to only really throwing pebbles at Google. As big as the iPhone is in the mobile market, it's still dwarfed by desktop internet usage. Google didn't get big because Apple had Google as the default engine on the iPhone. A bigger deal would be changing desktop Safari to another engine, but even then, there's Firefox on Mac, Windows and Linux as a minimum, and Google is #1 even with IE still being #1 (even if it is declining). Even if you were to assume iPhone and Mac numbers are the same, iPhone (and other mobile device) internet usage is in short spurts, not prolonged research like can be found on desktop computers.
If it was simply about sticking the finger to Google, they'd simply switch it to Yahoo, since it's already in there. There's more here than just saying screw you to Google.
Additionally, this is hardly a war. Google has limited avenues to retaliate. What are they doing to do? Push Android even more than they are? Apple owns two major platforms. Google owns one, and it has nothing in there which leverages Apple. About all they could do is dump their WebKit-based browser as Android's browser and replace it with something else like a Gecko-based one. Which is simply making a rod for their own back. Are they going to dump Chrome or other Mac apps? Make their systems incompatible with Macs? No, because doing so would be idiocy. It would be cutting off customers - they want more of them, not less, and replacing people's choice of online web services is easier than convincing them to replace an entire computer. And wouldn't help Google that much anyway. Would you replace your Mac with a PC just because Picasa or Chrome suddenly wasn't available for Mac? (If you would, I personally don't want to have anything to do with you.)