With all the information that Google knows about us and everything, they could in theory be doing a great job suggesting things that would be great for us - for example showing me a product or service I don't know exists which would help me with some problem I may be having.

Google pretends that it's what they do - showing the best possible ads for us. But what they do is the complete opposite, they find the best possible users to show their ads to. They have a responsibility to the ad, not to the user.