[Nexus One Q&A, Help & Troubleshooting] flarbear:
I agree with the basic premise that the Nexus One did provide leverage to potentially (and I think that is a key qualifier) keep the competition honest, but it isn't clear that it would do so without significantly more marketing. And, to market the Nexus One more could have annoyed some of the vendors that Google wants to keep happy - lots of happy vendors means lots of seats for Android means lots of seats off of which Google makes a lot of money. In particular, if every Android phone is locked, then Google still makes a mint, though they stand to make more of a mint if the platform is more widely adopted. And, an open phone does have an impact on platform adoption, but I don't think it is that critical since the public is used to buying fixed feature-set phones and upgrading for new features so this isn't an issue of taking away something that they demand as it is failing to give them something that they would come to know and love (as we already do).

But, I also want to counter some of the supporting arguments you present.

First, the current wave of smartphones was headed here one way or another. Google didn't create the wave, they simply reacted and targeted Android at the capabilities that were coming down the pike. To do that most effectively they needed a new developer phone and the Nexus One was going to be released in January one way or another as the ADP3 until they had this idea to sell direct. It was simply them needing to get out a testbed for the new Android capabilities that were targeted at the new baseline smartphone hardware and they chose to do it in an experimental new way this time. If they hadn't released the Nexus One direct to consumers then you would have seen the same phones come out and you would have seen the same OS releases, you just wouldn't have had a large installed base of end users previewing it on a non-developer handset.

Second, I think the main factor spurring the vendors to get 2.2 out quickly is that it offers so much, not that they have to keep up with the Nexus One. It is, in my opinion, the biggest release so far (and I've been with Android since 1.0) primarily because of the JIT. Also, all the manufacturers came out with what would become the new standard amount of RAM (512MB) and the existing release available for them to ship on did not support it, so they need to get on 2.2 in order to simply unlock the hardware they originally designed. In some sense, these phones were really designed for 2.2 - 2.1 was simply a stepping stone to get them shipped on their hardware schedule until 2.2 was ready on its software schedule. So, there are really 2 factors that would encourage them to get 2.2 out on their 2010-class phones that have nothing to do with the Nexus One being here.

As far as vanilla phones... The G1 was vanilla. The original Droid was vanilla (is it still vanilla with the latest releases?). The Nexus One was vanilla. But, where there any others? I love my vanilla phones (first G1 then N1), but I don't mind value added by the vendors, I just wish they would make it easier to customize things away and that they would learn to design their add-ons so that they can be easily dropped on to a new Android release with little fuss...