I don't see how Intuit has any pull on Canadian tax law or influence with the CRA. And there are plenty of alternatives. I used ufile.ca for years, way cheaper. And honestly, just picking up the form and doing it yourself is all my parents did for years.
I'm pretty sure we'll see what you're asking for within the next 5-10 years. With them already having the T4s, etc. I don't see why they couldn't have you login to their site, confirm everything, and submit.
According to someone who worked for a popular accounting software company, Canadian tax law is amongst the most complicated in the world. Many companies benefit from this, and it's long been shown that they lobby to keep it this way (in the USA at least). Assuming similar motives and incentives in Canada isn't a particularly big stretch.
But if what you describe comes to pass - even just for simple returns for individuals - I'll be pleasantly surprised.
I'm pretty sure we'll see what you're asking for within the next 5-10 years. With them already having the T4s, etc. I don't see why they couldn't have you login to their site, confirm everything, and submit.