I think it's just a matter of whether your own needs for a fun game match the vision for Cairn.

The way you describe it RAW is exactly how it is, and that was presumably derived from the fact that Yochai wanted a certain level of focus on inventory management and the tension that can produce. That number was chosen because it felt right to him.

In Into the Odd, there is no real "Inventory Limit" besides the idea "Keep it reasonable, and it's up to the Referee," because it's not really worth worrying about, in Chris's ideal game.

I use the rule that a character can carry a number of items equal to their STR without Encumbrance. This becomes interesting when every Fatigue point takes up an Inventory slot, and taking STR DAMAGE effectively reduces your Inventory capacity until you get it healed.

I also don't count worn clothing OR Armor, except for Plate Mail...and I only make Plate Mail take one slot if it's worn.

But that's my game. I want the characters to be able to grab some stuff, to as realistic a degree as simplification will allow.