OK, but what's softer... your spring steel leaf pack, your steel spring perch, the steel center pin, or the aluminum shim? The shim's center can still be wallowed, and thereby allowing movement, or any number of other problems.
Not to mention, I've not seen a centering pin with a head long enough to do what you've described... not saying they don't exist though.
But I don't run shims, only going off what I've seen happen on the trail, and what the resulting part looked like.
you can purchase longer pins @ any auto supply, mine go all the way
threw the axle purch, been running that way for years no problem.
most people over look the pin going threw purch, i could understand
them puking out.