I'm sure this commit was largely motivated by business reasons, but it seems pretty reasonable from a forward-looking technical standpoint as well.

Google search on Android has gone far beyond an endpoint where you give it a string and it gives you a list of URLs; it gives smart autocomplete, you can search by voice (which is smarter than speech recognition + text search), it provides custom result widgets for various situations, etc. As the feature set expands, it becomes less and less reasonable to have a single client that works against an abstraction implemented by many competing backend services, so the idea of a "search engine picker" makes less and less sense. It's saner to just say "this is the Google search client, and other search services can write their own clients". For example, Bing has its own Android app with its own design and features not in Google search. (That's not to say it's fair; Bing needs to be a separate app, whereas Google search is a first-class part of Android.)

Yes, but I don't think that is true of this feature:

1. It's a feature. Features have inherent maintenance cost. A team can only support so many features, and new features generally come at the cost of other features being well-developed. A significant part of my day job involves killing features that technically work but require so much maintenance overhead that we can't effectively work on new things. This makes some existing users of those features unhappy. We're killing them anyway.

2. The change improved the level of corporate support for Android, thereby improving Android's future headcount and budget, thereby improving the ability for other features to get delivered. Trashing that on principle does harm users. There are plenty of dead and dying mobile OSes with a customizable search engine that aren't helping users in their current state.

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.