I think it's a mistake to think that people who visit your site somehow 'owe you' and should permit third-party tracking code from your site to run in their browser. I understand your points about wanting metrics to learn from, but when you bring in a third party all bets are off and individual visitors (like me) will choose not to run that tracking code.
Don't forget there are other ways of achieving what you want too - you can use something simple like GoAccess[0] or even run a Piwik install off your server logs[1] for a nice pretty GUI experience if you prefer.
As more and more people become privacy-conscious I hope you will see this as an opportunity to learn how to do more yourself and outsource less to Google. They don't even give you all the data they collect from site visitors, you are giving them free data for little in return!