What did you Expect
What did you expect - a magic, learning voice recognition assistant?
Of course they are going to keep samples to run algorithms against and of course they are going to tee answers up for questions which are being asked a lot. What do you think the Siri guys are doing with thier time?
If you are so concerned about your private details then you should get off the internet, and certainly not use a mobile phone. The privacy cat is out of the bag, either get on with it or stop using the kit. No-one is forcing you to use Siri, or GV, or any other flavour of voice recognition app, service, photo storage, mail provider etc etc etc. Before you register for any serice, or use any service, you should be of the mindset that your data will be collected, analysed, possibly sold on and stored. Once you have this in mind, you can make a decision based on which services you want to use based on this trade-off.
You pays your money you takes your choice, or in the modern world - you use a service you hands over your data.
There is no point complaining though, else things will not work very well, or you will need to pay for them.