The 17 Pro has a much higher resolution camera than the 13 Pro, so even if you center crop of a photo taken with the 2x optical zoom to get you what you'd see with a 3x, it will still be higher resolution than the same photo taken with the 13 Pro.

That said, I too like a 70 mm lens, but I long ago got used to just moving closer to or further away from subjects to take photos with dedicated cameras depending on what lens I had on.