I'm not sure what kind of photography you do, whether it is work with models or families or children. The canvas backdrop looks nice in the pictures but I think a big part of it, is that there are gorgeous models who have had half a dozen stylists working on them for hours standing in front of it. They could be standing in front of a hanging Lion King bed sheet and it would look good. Imagine placing a "normal" looking person in front of that background and it won't be that spectacular. I think it would actually look worse than getting a standard muslin because the canvas they are using isn't seamless and only works because the fashion photograph is about an interplay between textures and quality--the photo shoot itself is part of the aesthetic of the image and you can tell they wanted it too look a little gritty, compared to the clean, flawlessness of the models. If you had a canvas with stitching running crosswise through it in front of a family portrait, you would have some confused clients.
Personally I dislike fabric backdrops of any kind and think they look terrible 90% of the time. There are some nice ones out there but they are few and far between, and to have a photographer use one well is ever rarer. Look at photographs inside magazines (not just fashion magazines, but any magazine where there would be portraits of people, which is any) and count how many fabric backdrops you see. Very, very few. Either the portraits are taken on location or in a studio in front of a cyc wall or in a set they built. I don't understand why fabric is so popular. Most of the time it looks like a psychedelic hanging bed sheet and smacks of school photos from the 70's. Plus many photographers are using crop sensor cameras and cannot get the background out of focus, so they look even worse. Fabric backdrops have there place and I think they are working magically in the Italian Vogue fashion spread. But as a slapdash, default background, I think people should try a little harder. I assume we are trying to create art and not glorified DMV portraits.