My two cents:
To see where I'm coming from, I'm nearly 40, grew up with the ZX Spectrum and Commodore 64. And yet, even back then, I spent a lot of time making games for my friends. Or, uh, making the ZX Spectrum draw circles on the screen. (hey, this was the early 80s, and I was 8.) :p I've always loved creating stuff, which made me become a writer when I grew up. So when BioWare announced a game called Neverwinter Nights, I was in love. Skip ahead to release day, and you have a problem. The game was boring. Very, very boring. So boring that I barely played it a week. But for those of you who don't know the game, it was mostly an editor, with a game slapped on well into development. And it was the editor I wanted in the first place. So while the game barely lasted a week, the editor lasted four years. I had a lot of fun with it, and even learned how to use the programming language in the editor to make my own cutscenes, scripted events and so on.
And now look at Disney Infinity. I think the playsets are more fun that I expected, but they are not why I bought the game. I bought it because of the toybox mode, and because we could... should, sorry... be able to share our work with the rest of the world. And yet... we can't. I sort of hate this, and sort of don't mind. The sharing has to be included soon. That's not even a request anymore, but closer to a demand. You can't have a game that focuses so much on creating stuff, and then not let us share it. That's like someone making the best digital camera to date, yet restricting the pictures to the camera only. It doesn't make any sense.
But nevermind that, this is about the toybox. I do love the toybox, and I think we can create a lot of fun stuff simply by playing the playsets a few hours. Plus, you can get 16 spins (easy if you have multiple characters), shuffle the vault to find something you want, an then be guaranteed to get it. So give it a few hours, and you'll have some fun pieces to play with. But is that enough? No. Not by a longshot. What I think they should have done is split the pieces in three: there's the themed stuff found in playsets, random stuff that doen't fit in any particular theme, and essential stuff like creativity toys.
Themed toys: Should be unlockable by getting the playsets only. If you want Lone Ranger stuff, get the Lone Ranger playset.
Random stuff: Should be unlocked by the vault only, as none of this is 'required'. Besides, after a few hours, you'll have a lot of this anyway.
Essential stuff: All of this should be unlocked from the start. Triggers, buttons, race starts, counters, you name it. If it's a mechanism required to create a better playset, it should be unlocked from the start. No one wants to spend six hours creating the best race track possible, then spend another twelve hours in playsets trying to unlock a way to actually play the racetrack they created. Making a 2D platformer is fun, but spending a few hours trying to unlock the 2D camera is not. And it's pointless anyway.
So for Disney Infinity 2, it's really easy: Keep the essentials unlocked from the start, then add more and better optional stuff for the vault. Oh, and let us share it right from the start, too. Thanks.