It's definitely something to keep in mind. As someone already mentioned, rope halters are not mild. Good riding technique and soft hands should still be in effect, you should never be hauling around on a horse with a rope halter. (Regardless of what the horse is wearing you should never be hauling on their face obviously).
I once read an excellent article that outlined all the possible damage you could do to your horse's face with various nosebands. In the ongoing debate of bit vs bitless, there are lots of articles about the damage to a horse's mouth with the bit, but people neglect the fact that horses can also feel the outside of their face too. If I find it again I will post it.
Fit is a huge factor too I feel. My halter should be snugged up high on her nose, and her bitless noseband is higher than recommended because I do not want it sitting on the soft part of her nose.
It should all be about the horse's comfort. My girl loves her bitless and will literally stuff her face into it when I hold it up, even right after I have taken it off!
As for the halter, same thing! It gives light, consistent signals without having to apply a lot of pressure.