Some of us have had enough battles with red mites that we don't want to give them any more hiding places. And long acting permethrin sprays do not work on the ones I've been battling. I now have painted, removable roosts to reduce the places they can hide and the ease with which I can treat...
I'm familiar with that article too but the only problem with adding things to the outside of the perches is if you have an outbreak of mites it gives them lots of cracks and crevices to hide in and avoid the treatment that will kill them.
I found this very in-depth write up on aspects of animal welfare with respect to perches in commercial egg laying facilities. It is very long but here are the conclusions that relate to this thread:
There is no consistent evidence from the literature on perch shape preference (e.g. round...