I do not know who is responsible for the use of double brackets for subscripting.
Anyway, the use of brackets seemed marvelous back when cave men only had parentheses to scratch out on their damp walls. My suggestion is that a simple pull-down menu be established that offers multiple choices for grouping symbols. We could have parentheses with a bar at the top, a bar at the bottom, both the top and bottom. Think something like If "open paren with top bar" blah, blah, blah "close paren with bottom bar." The wonderful double bar for subscripting be replaced by a single open bracket with a circle in the middle, followed by a close bracket with a circle in the middle. Dan Lichblau of Wolfram has suggested different colors. That would also be fine, also. Do away with the Chinese torture practice embodied by braces, microscopically distinct from parentheses, unless they default to a different color or bold type. Why not replace every usage of bracket pairs, Do-loops, If's functions, etc, etc, etc, as the King liked to say in the King & I.
I had a nightmare, wherein I was trapped between a close bracket and a close brace. Sound familiar? Clap your hands!
Thanks, Chris Niemann
The following link (some keyboard shortcuts) based on posts by Szabolcs and Mr. Wizard more than greatly reduce the torture of entering pairs of those symbols. And I agree with David Park: magnification is a great thing.
It's not that bad. Maybe you want to increase the magnification for your notebooks.
The palette that comes with my Presentations application has, on the main face, paste buttons for round brackets, list brackets, square brackets (click twice for parts) and text quotes.