[Nexus 6P General] cb474:
I suppose there's no reason not to include a feature to disable noise cancellation, if some people find it useful. But I wouln't say "most phones" once had this sort of setting. I can only think of a few Samsung phones that had it a long time ago. It's a pretty unusual feature.

That aside, as I often note, actually the Nexus One has amazing noise cancellation. It used the Audience chip (called Earsmart now) which is leagues better than Qualcomm's Fluence. Fluence has always had issues. Motorola also does a decent job. The 2014 Moto X and Nexus 6 have four microphone noise cancellation. Though Motorola tends to favor less noise cancellation in order to have more natural voice quality. It tends to be a trade off between a slightly processed sound to your voice with strong noise cancellation or a more natural voice with more noise coming through.

But Qualcomm's Fluence is really mediocre. Yet since it comes built into Snapdragon chipsets and they are so common in phones, Fluence has become by far the predominant noise cancellation solution. That's why it's so bad in so many phones, because it's really all just the same problem, which is Fluence.

It does seem like the mic placement below the hump has caused more issues, by being blocked, than tends to happen on other phones.

To be fair, what Bose does with headphones is actually a lot easier than active noise cancellation in mics. They just need one mic on the outside of the heaset to identify background noise, create the opposite sound wave, and cancel it out. And they know very accurately from the sound input in the headphone jack what is the sound not to cancel. On phones, capturing your voice in real time and accurately differentiating it from other sounds is much more complicated. So I don't know if Bose could offer the magic solution.

That said we don't need Bose. As I mention above Audience already has set the industry standard. Their noise cancellation chip works really well. And it was used in the Nexus One, which may have been the first phone with that chip and one of the first with active noise cancellation. The Nexus One had amazing noise cancellation. No weird issues and all the time when I was in some loud cafe, people I was talking to were amazed and said they thought I was at home. The Nexus One with the Audience chip had noise cancellation that was so superior to subsequent phones it's ridiculous.

The iPhone 4 also used the Audience chip, following in the Nexus One's footsteps. But then insanely both Google and Apple dropped the Audience chip. I think the Nexus S had no noise cancellation at all. The iPhone 5 shifted in an in-house Apple noise cancellation solution that is inferior (and more sophisticated reviewers of Apple noted it at the time). That left, for a while, only Galaxy S and Note phones with the Audience chip. But now with the S6 even Samsung has dropped it. I guess they don't want to pay licensing fees.

In any case, the Audience chip is really incredible and it's crazy that no one uses it anymore. It has been all downhill for Nexus phones since the Nexus One. One problem, I think, is that reviewers don't test noise cancellation and comment on it. AnandTech used to do great tests and acknowledged how superior the Audience chip is, but they can't be bothered anymore. Everyone has just accepted the status quo.

Anyway, so noise cancellation truly is a problem that has been solved, but no one can be bothered and no one wants to use the existing solution offered by Audience.