Limitations

They are inventory items and you could actually put them in your inventory without opening them (seen it done through crashing). Is this that big of a deal?

 

There's reasoning behind this, actually.

If you hit "claim crate" and then your device locks up or you lose connectivity (eg: playing on a train, it goes through a tunnel) then the box is put into your inventory.

That way you get to open it when you reconnect, rather than it just being lost - or looking like it was, if the resources/items were just silently added to your inventory.

So while it's a nuisance, it's actually there to ensure that you always get your goodies.

 

But when buying epic crates (or opening multi-item crates) you always have to have at least that one open slot in your inventory. Even if you're going to overflow by 9 items (eg: buying the epic crate) you still need the one space to hold the "placeholder" item in case you crash out.

obligatory not-a-Rovio-dev-but-a-dev disclaimer

It's a user-experience issue. Even though the free crate only contains pearls, sugar, and gold - three resources that you "always have room for" in your inventory, if they were to be silently rewarded behind the scenes, and then a player experienced a crash/disconnect, they might get the impression that they didn't get the rewards; because honestly, do you look at your current gold/sugar/pearl count before hit the "claim free crate" button? I know I sure don't. So rather than risk a bunch of people getting upset because they think they've been "robbed" of their resources, it takes the safest approach of "if they crash, put the crate in their inventory and let them open it there."

I thought it was silly myself until I had that situation happen due to the office WiF... I mean, my home router, I'm not playing at work I swear ... cut out and I went "aw damnit did I lose that?"

Nope. Box was waiting in my inventory when I logged back in on LTE. Felt good.