Oh yeah, the sandbox aspect is cool. We're mostly just criticising that this game is ONLY a sandbox, and is too expensive for something that's only a sandbox with no game elements.
Minecraft is a sandbox but also a game. There's challenge in finding food and battling creepers. The reward for time invested is a safe home and big farms - i.e. you can overcome the challenges to construct cool buildings and such.
I'd like to play Scrap Mechanic, but at this point it just doesn't have enough features or challenge to justify the cost.
I dunno, I guess we're just different. I kinda hated the survival aspect of Minecraft. Like, I'm building my stuff and exploring, why does some creeper have to get up all in my face and explode and destroy the stuff that I've been creating, along with myself? I dunno, I really enjoyed Minecraft even when it was free (?) and just had a dozen types of cubes? Not even picks... just adding and removing bricks - left click and right click. I also remember playing "Conway's Game of Life" for hours when I was a kid.... or The Incredible Machines in free build mode.
To just outright say the game is shit because they give you tools for you to tinker around with is... not very objective, I guess. It's a sandbox game, where you can geek out and build complex stuff, like houses that transform into cars and stuff like that, or whatever you get your mind around to doing. It sounds really cool. For me. Maybe not for others.
I'm not gonna pay $20 for it, because there are already a billion games kind of like this that never really go anywhere, so the track record isn't amazing. But that's more of a statistical analysis of the potential for a project's technical success as opposed to a criticism of the game design itself.