Yes, we have a difference of opinion on these
Regarding the facts:
1) They also come from America, so origin is immaterial
2) The shape is not consistent with ancient ingots, so symmetry or depression also does not matter
Regarding the findings:
1) Definitely NOT cast in a crucible. The depression is the wrong shape to be derived from solidification shrinkage, the internal porosity is in the wrong place to be associated with the depression.
2) & 3) also immaterial
Regarding the open questions:
1) Choice of grinding media is governed by hardness and specific gravity of the material to be crushed, there is no reason to think cast iron is more common. Several types of cast steel shot are commonly available.
2) Because we have evidence of cast steel being used, it clearly must be one of the economically viable options, no need to ask why.
3) This is immaterial, since there is no reason to think they are ingots, why speculate on how they wear away in the mill? But there is no reason to assume the process is not random, generating symmetric and asymmetric forms.
4) This will of course be a good idea!
I admit my opinion is colored by having first run across these in a very non-wootz context, but the shape of the ones sold from India and some of the ones I found at a mine in the US are identical.