We can debate the usefulness (or lack thereof) of the eTA program until the cows come home, but the reality is that it remains the responsibility of travelers to inform themselves of all applicable entry requirements when going abroad. I have little sympathy for people who do not spend 30 seconds informing themselves of the requirements and are held up at the airport as a result. Especially people who are traveling for business and need to check whether they require a work permit.
As far as requiring dual citizens to get a Canadian passport - cry me a river. If you want to avail yourself of the rights and privileges of Canadian citizenship you also need to pay for the documentation. Even a birth certificate isn't free.