@Midoriha I disagree with your first point. As far as moral high ground goes, when there is no english and the scan it for 'free' (Donation earnings or ad money isn't counted because you are not forced to pay anything), it provides 'advertisement' for the author while effectively "stealing nothing".
When the series gets an official licensing, the author gets paid so it becomes stealing, causing authors to drop stuff entirely.
On more realistic views, continuing after it is licensed is 'against the law' and may actually get them into trouble if the author pursues the issue. At the very least, they have less "protection" then when the story isn't licensed. Whether they actually get sued or not because court cases are a huge hassle is a different matter entirely.
There are also times where an author contact them personally requesting them to stop. (happened to a Soap Saint series)
Everything is fine when people "don't care" but the moment people start "caring" is the moment all the problems come.
They are probably other reasons too but I am too lazy to think. Law is usually the biggest one.