Whether it's worth it is entirely up to you.
With that said, the 500mhz difference in max boost, along with the IPC increase with 3rd Gen Ryzen is gonna give you a nice little FPS boost with your 1070ti. Maybe as much as 15% game dependent. Also for newer AAA games the extra cores and threads will help. Games like BF V will be a lot smoother too.
What ram set up do you have? Ryzen likes fast ram, and dual channel.
At 1080p, you could go high hertz with a 3600/1070ti combo, and touch 144hz in the majority of games. Maybe not the newest, but would still be a nice experience all the same.