We should be allowed the option to buy a backpack to expand our personal inventory

[TechnoTheFirstTTV]

Not going to lie, while this game is thankfully generous in your mobility, being unable to carry more things can still be a bummer. So a backpack really could be an option to expand said inventory.
Make it a slot to equip something into that can (obviously) expand your inventory at the cost of speed or visibility.

[Sistermatic™]

It's in the roadmap. Might be worth a read instead of a thread for every idea.

https://trello.com/b/VQQpru3F/schedule-i-roadmap