I'm not sure from your comment whether you're just being pedantic in pointing out that while regrettable this isn't surprising (in which case your comment is not very constructive), or whether you actually think it's OK for Firefox to do this.
Since you've used the term "anonymised" quite pointedly, I'm guessing the latter. I do find it surprising that anyone would assume data Google is collecting on your usage is somehow anonymous.
More along the lines of: I now fully expect the cost of entrance for free applications to be data the developers collect of my usage. It's naive to assume otherwise.
That's the case for some, but (1) most applications that lean that way are likely to be closed source as there is a certain sense of apparent moral high ground that comes with open sourcing and (2) more importantly Mozilla sells themselves on respecting privacy, first and foremost.
> I now fully expect the cost of entrance for free applications to be data the developers collect of my usage.
Apparently this is also true of applications & services you pay for these days too. Includes ISPs, cell companies, cable apps where you input your customer code, paid subscriptions to online news... the list is endless.
Since you've used the term "anonymised" quite pointedly, I'm guessing the latter. I do find it surprising that anyone would assume data Google is collecting on your usage is somehow anonymous.