If you offer the option to disable telemetry, some people will disable it. If there is any pattern to which people do this, and we all know there is, it introduces sampling bias and casts aspersions on any conclusions you draw from that data.
Personally, I'd probably be satisfied if Microsoft gave me the tools to examine the telemetry that my computer wants to send. Not making that available to users makes me feel like they have something to hide.
They also tell you exactly what types of data they collect, along with where and how. That's not consistent with wanting to hide the extent of their telemetry.
where?
This is the Windows 10 retail EULA: https://www.microsoft.com/en-us/Useterms/Retail/Windows/10/U...
It links to "aka.ms/privacy", which takes you to: https://www.microsoft.com/en-us/privacystatement/default.asp...
There are some good examples of the categories of data that they collect and some information about which features, programs, and apps might collect that data. There are examples within the categories, but not an exhaustive list. Maybe there are more complete lists available for each separate feature. I'd be interested in seeing an explanation, collected into one place, of which pieces of data are influenced by which settings, which ones can't be controlled, etc.
https://technet.microsoft.com/en-us/library/mt577208(v=vs.85...
I've seen hand-wavy explanations, in general terms, of the data collected. I don't want that. I want to see the actual data collected from my specific machine. Even a bullet-point list including items like "total time executing binaries tagged as 'game'" would be preferable.
Users who turn off telemetry can still give you one crucial data point: the percentage of users who do care enough about privacy to turn off telemetry. But this data point is something they simply can't capture because of their insistence on making telemetry mandatory. And any future decisions they make with regards to privacy and telemetry usage will now have to be based on speculation instead of hard data.
In addition to biasing their telemetry data to the subset of users who don't care strongly about privacy, this decision also has a real cost in terms of adoption rates, market share, and damage to the goodwill they've slowly built up over the years in other areas. I just can't see why they'd think this is a worthwhile tradeoff.
This is true enough, but consider this: Giving the option to disable telemetry will result in users users who would disable it. Not giving the option to disable telemetry will result in users who who simply won't use Windows 10 because of mandatory telemetry.
With the former option they still get a data point in terms of the percentage of their users who care enough about privacy to turn off telemetry. With the latter option they don't get this data point, but in return they get some telemetry data from users who would disable telemetry if it was available, but don't care enough about privacy to use a different OS because of it (i.e. the telemetry data they have available is still biased to the subset of users who don't care very strongly about their privacy).
Is the data from this latter group of users important enough to be a worthwhile tradeoff for getting data on the percentage of your users who do care strongly about privacy and the damage to their market share and the damage to the goodwill they've built up over the years? My answer would be no.