When you compare dowel to a natural branch, no matter where the bird perches the pressure will always be in exactly the same place on the foot. Also, it being nearly impossible to find a vet that wouldn't think you're nuts for wanting your birds nails trimmed (my first experience at an avian vet's was a bemused expression followed by "you do know this is a bird, and birds have sharp nails for a reason.....) Providing natural branches of various sizes is a great way to keep those nails down. Besides it's not that hard around here...there are trees everywhere.
But this is also my personal preference...I would prefer to see my birds on natural branches, for some reason it leaves me feeling happier.
Just my 2 cents
I do love those cages...going to see if I can price some around here