When doing yoga, everyone needs to know and understand their limits. I know there is a lot of pressure, personally, to reach farther and twist more than you should whilst doing yoga. The straps are there for a reason and it shouldn't be viewed a weakness to have to use one.
When teaching yoga, the instructor needs to know and understand the limits of the human body. And then, at the very least, need to make sure their students know not to exceed those limits.
