I’m not sure that I fully understand what you are talking about.
As stated in my post above, you can use grappling hooks to descend a z-level safely.
They can also prevent you from falling into a sinkhole.
Why would you ever want to descend into a pit?
And throwing them upwards may still come with the continous improvment of z-levels, and I’m not sure that you should be able to “climb up just about anything” with a grappling hook. First, it takes incredible strength to scale a vertical wall on a rope. Second, the hook needs a position that it can reach and jam itself into. As anonanon stated a post under mine, it’s also already possible to ascend a z-level (verified in experimental version 0.E-10907).