I hear you on these items and am already thinking about solutions - since I've heard them before!
- Slow pace of climbing
- Mark already collected crystals and scans
- Faster stamina recharge
But regarding letting go, I will keep it as is - you'll probably get used to it over the length of the game :P
And grappling is only in the last level (and maybe a crystal level too).
I couldn't really fit it into the story without making traversal too easy, but demand was high so I had to have it lol.
I will likely release some custom maps later as well as DLC with more grappling.
Also planning a free level editor (but not on release), so you'll get more grappling and late-game mechanics to play with :)
Thanks for taking the time to leave feedback!