It's a great concept -- choosing equipment wisely -- but it wasn't pulled off well in SS because of the limited inventory. I think the idea behind Adventure Pouch + Item Check was to create a sense of planning and procedure.
[None of the following is in SS as far as I know, this is theory talk]
Say the next area you have to complete is Snowhead, which is an ice themed area. Your current status looks like:
15 heart containers collected from heart pieces/boss rewards but a total of 16, standard magic meter [can only be doubled via Magic Badge], ice arrows; hookshot, boomerang and so on are in Item Check.
In your pouch you have:
- Heart Medal -- Gives an extra Heart Container [for a total of 16]
- Ice Arrows [it's an attachment sort of, almost like a medal in and of itself]
- 2x Bottles with fairy and green potion for magic meter restoration
- Wooden Shield
- Fire Tunic
If you ran in as you are, you would experience certain areas of Snowhead that are inaccessible because you lack X equipment, but you can still *complete* Snowhead because the game isn't linear in that sense. You would likely encounter a plethora of ice themed enemies but since you're using the Fire Tunic, you would take double damage from ice enemies due to a type advantage (this isn't Pokemon but don't act like weapon triangles and such originated from it).
However, if you ran back into Item Check, switched Wooden Shield with an ice-based shield (ideally at this point you'd have one), switched your fire tunic with an ice tunic, grabbed the hookshot and maybe switched ice arrows with fire arrows (the point of an themed dungeon hero is to be the dungeon theme's antithesis in offense, but the same in defense), you would have a much easier time and be able to explore certain other areas in addition to or at the cost of the areas you were able to explore before.
[/endintheory]
This obviously wasn't the case. If SS were developed on a bigger system, I'm sure we would've seen a fleshed out Adventure Pouch + Item Check system. Nintendo meant good things with introducing it, maybe it should stick around for Zelda Wii U/3DS. I like it, anyway.