iOS 12 introduces this feature to devices without 3D Touch. Just press and hold the space bar until the characters on the keys disappear.
So three years after its introduction, its only major use is for moving between text. And if it were so good you would bet all the Android phones would have copied it. And so far none of them did. If by 2020 we still don't have an killer feature for this I question whether that extra $15-20 BOM cost as well as internal space for battery is worth it. Subtracting some display cost for supporting 3D Touch, we are paying roughly ~RSP $50 for this one feature.