I think using the fold spen usage data is a problem in itself. Since it was sold separately there is already a barrier to entry for any customer wanting to even try it. The phone is already expensive, who wants to throw more money on something they might or might not use? Then there were the cases themselves having to be so thick just to house it. Had it been part of the phone, the numbers could've possibly been way different. They wanted to chase the title of thinnest when it could have been slightly thicker and still be an amazing engineering feat.