It was definitely one of my favorite features, and Force Touch isn't a drop-in replacement.
With 3D Touch anywhere on the keyboard, you could apply pressure to start moving the caret (text cursor) around, but what was even more useful was being able to apply a little bit more pressure to start selecting text with incredible precision.
With Force Touch, you can long press on the space bar till you get haptic feedback, then you can move the caret around freely. However, if you want to select text, you need to use a second finger on the keyboard after you start moving the caret around, but honestly it's an absolute mess to use; try it out, I can guarantee you won't be able to select what you were planning on.
However, as much as I miss it every time I fail to accurately select text on iOS, I don't mourn its loss. Force Touch is adequate. It's just not a replacement, and seems a shame it was probably removed to reduce costs and hardware complexity, all at the cost of regression.