Some owners may not have or would rather not use those OEM steel wire fasteners. The round plastic fasteners require a different shape hole in the panel.
One word of caution. If you use the stamped (not the wire ones) replacement clips with the yellow-ish goo on them. Take the goo off. I tried to install my new panels with them and the goo forced the clip to cut through the vinyl.:x
Once I removed the goo, everything went smooth, accept for the rips in my new door panels......
Yes, I have all Legendary Int in my car and it's great.