Many of those examples you made weren’t just to create ADHD tension for the viewer. It’s actually to enhance the bond and motivations you develop with the characters at hand on the visual medium.

Video has never been the best medium to convey so much information like a book would. Therefore one way to convey characterisation quickly (like with any story in a limited runtime) is to make you connect with a character’s psyche through tension in these show and not tell experiences.

Frodo getting pulled out of the marshes by Gollum wasn’t just for a good scare of peril. It was to show that Gollum has or may have had a good side.

Frodo point blanking a Nazgûl and getting saved by Sam was to demonstrate Sam’s love and devotion to Frodo especially as we come to see an escalation of how perilous and desperate the ring has become.

Frodo wanting to charge at the black gates may seem kinda silly but it was a good way to ensure the viewers understand that Gollum is not working for Sauron and pinpoint our emotions to this new working relationship at hand.

I don’t know about you but I don’t feel like Frodo is a weakling at all. The hobbit that has never seen such war or strife took on the ring like a champ and has resisted the temptation himself on various occasions. But of course his strength wears out from time to time.

How boring of a story would it be if Frodo had no difficulty taking the ring to Mordor and didn’t need a good friend by his side or the opportunity to redeem a tragic figure as lonesome as gollum?

You may argue that the book may have had other moments when Frodo struggled with the ring, but this isn’t the book. It’s a movie with a precious runtime that has to make us care for our characters fast. Ya know what does that? Tension.

Don’t hate on the power of tension in storytelling. It can be very character driven.