The fundamental problem with Force Touch and 3D Touch is that it relies on the assumption that uninformed people who accidentally happen upon the feature (by pressing too hard on a link or icon, because they’re in a bad mood or have imprecise motor control or whatever reason) will wonder what happened, ask around, figure it out and either be delighted or turn it off.
But that’s not how regular users work — especially when you’re at the point where each iPhone iteration sells hundreds of millions. Many of them will see their device behave erratically, both blame it and blame themselves, then carry on with their day, muttering “goddammit those fancy smartphones are stupid.” Maybe they’ll find out about 3D Touch months later, when it happens again in view of someone better informed — but by then the damage will have been done, they’ll have lost trust for their device.
It used to be that a Mac user’s first line of technical support was That Geek Friend / Family Member Who Had Made Them Buy A Mac In The First Place. But the iPhone is far too ubiquitous for that model still to work; many users don’t have a designated geek anymore.
It also used to be that Apple mostly avoided that kind of mistake.