I live in an apartment; I have a bunch of unsold paintings hanging in random places from when my boyfriend went on an art-hanging rampage (I was away), and I just don't have the space or the capacity to bother with rolls of canvas right now. I know it's better in many ways, but it's not better for me.
However, buying canvas, especially in odd sizes such as the 3x9 projects I'm working on, can be annoying. Even art stores have customers in them who might pick up a canvas and 'dent' it, stretching out a piece and distorting it. A canvas is like a notebook. It should be treated with respect, because you're going to fill it with valuable content. Shipping artwork is also difficult because even the best intentions in packing can go awry.
Thankfully, it's easy to fix these problems with a spray bottle of water, a towel or paper towel, and patience. It might take a few rounds, but if your canvas gets a weird dent--not a hole--you can fix it by spraying with water, wiping off the excess water, and waiting for it to dry back into shape. The same is true if you're fixing the distortion that a hole has caused in your canvas.
I always get frustrated by how slow the process takes. I've been wrangling my 3x9 canvases all morning because the stretcher bars are so large relative to the 'open space' where the back of the canvas is exposed. You may have to wet the canvas behind where the bar is by putting your fingers underneath the bar and spreading the water in there. Of course, improper ventilation means that you should use artificial airflow to get in there and dry it faster, or make sure that you're not in a humid climate. You may actually have to stretch out other parts of the canvas in the process of getting the entire back to tighten.
Anyway, that's why I'm sitting here, annoyed at imperfections that realistically, I'm the only one who will notice, waving around canvases like they're glowsticks and I'm the last idiot at a rave.