It's also not a realistic scenario.

Anyone who bought a Samsung Galaxy S from Verizon got a phone with Bing as the default search engine. Some of the people who bought that phone would've preferred Google.

Because of this feature, there was added additional effort in using the phone due to the need to switch the search engine. And likely some of them didn't even know about the option, and wound up with an experience worse than they would've without it being present.

Adding to this, there is malware that changes this setting.

I think this was a valuable option to have -- but there are no features that cause zero trouble to anyone.