Firstly that often results in horrid UX experiences, as Google Instant is. It is also, weak for the following reasons:
1. No innovation happens (which is why Apple came up with the smartphone touch UI and Google just copies it)
2. People don't like change, so will favour things close to what they had before
You have fallen straight into the same odd thinking dominating Google, that UI is incremental, testable and easily measurable.
You want precise and measurable. That's not design. Jonathan Ives is worth his weight in gold for his design skills as much as Linus Torvalds is worth his weight in gold as a programmer. And we as engineers have to accept that.
Google will never come up with a great design with the way it approaches the problem. While I love their products, none of them have ever blown me away because of their elegance or coherence. They only know how to do simplicity and are beginning to forget how to do that too.