What do you think of my voxel editing and scenery creation tools?

http://www.youtube.com/watch?v=GjSasJlp-7E

Would really appreciate it if you could answer this question for me... and also would you like tools like this available inside the actual game and find them useful while playing? i.e. Abstracted away from the actual 'game' elements.

Comparing and contrasting to Minecraft; I like the idea that all editing and creating is done while immersed as a player (i.e you carry around blocks and have to actually walk to where you want to place them, etc...) but personally I felt this stifled my creative abilities and made creating stuff a bit of a pain in the ass.

Obviously I will make my interface more game-y and much more user friendly, but as a concept would it be good to have a mode like this, where you can edit much more freely and easily?