Inventory System

Hands down it's scrapping the weight-based encumbrance system for one using inventory slots. The quick and dirty version:

You have a number of inventory slots equal to your Strength score

Most items take up one slot.

Smaller items can stack (typically up to 3 or 5 to a slot, whatever makes sense) and tiny things like pieces of paper or whatever take up zero slots.

Larger items like heavy and/or two-handed weapons take up 2 slots

Light armor takes up 0, medium armor 1, heavy armor 2 slots

100 coins per slot

Ta-da! Tracking encumbrance doesn't have to be a sloggy bookkeeping exercise, and limiting the amount that can easily be carried can lead to a lot of interesting decisions in play. I'd go so far as to say that some sort of inventory management/encumbrance tracking is crucial for any wilderness survival campaign, and most any campaigns with an emphasis on exploration. The current system is excessively granular to the extent that most people understandably just hand-wave it away, but I feel like we miss out on what can be a very fun element of the game when we do so.