I'm not sure I would classify this a epic failure. This feature was enabled, and used fairly widely. It didn't live up to it's potential, and the biggest issue

I'm not sure I would classify this a epic failure. This feature was enabled, and used fairly widely. It didn't live up to it's potential, and the biggest issue may be the weight / thickness requirements that it put onto Apple products. Apple traded that weight / thickness for more batter on the current phone, which is well worth it. I miss 3D touch with the newest IOS builds. All that said, the discoverability aspect is huge here. It either needed to be built into everything, or nothing. Lukewarm adoption here was a major issue, because it meant that users had to experiment to discover what was actually possible.