In short, this is only interesting for period tailors.
Period tailoring? Gasp - the horrors!
A lot of European men's tailors (German, Italian - and obviously Dutch) don't cut canvas on the bias. However, Claire Shaeffer has said previously that the Parisian haute couture ladies' houses such as Chanel do still routinely cut their canvas on the bias. I understand that this is to create softer lines. It seems that Anglo-American men's tailors also adopted this ladies' tailoring technique last century on so-called "soft coats".
The theoretical reasons for this are explained by Whife and Cunningham. So I am curious to experiment with trying this out on a soft summer coat. I have already started to test a canvas from Tessollino Zorloni Bruno out for this.
However, I agree that beginners should start with cutting conventionally on the straight, unless they have a real life teacher who instructs them to do otherwise. This is especially true of modern canvasses which are already sufficiently soft without having to cut them on the bias.