Very new to the site so please bear with me. I would love to post a picture of my MMO concept that I built and gather opinions on it. I can take constructive criticism, but I guess I'm afraid of the thought of someone stealing the idea? I would love to post it though.
If you want open-ended opinions on your game, then this is not the best site to gather them.
StackExchange Q&A is geared toward solving concrete problems, and questions that have a concise correct or working answer. Opinion polls don't really fit our format.
You can try a more open-ended discussion site like the forums on GameDev.net, or earn a little rep here by asking & answering questions to be able to access our informal chat rooms.
Generally, I wouldn't worry about someone stealing your game idea. Especially for something like an MMO, the idea isn't the hard part, it's the years and fortune invested in implementing and executing those ideas. Everyone who's ever touched a game has more game ideas than they'll have time and resources to make in their lifetimes, so there's an excess of supply, and everyone would rather make their own ideas than take yours. (At least until you've done the hard work of proving it's commercially successful — that's generally when the clones show up. Until you're making money or rolling in heaps of users, nobody cares)
Or, to put it a more bluntly, your game idea (probably) sucks. And that's OK. Most ideas suck. It's the process of refining, improving, executing & building on ideas that might suck on their own that eventually makes a great game. No one can replicate all that hard work from a few concept images alone.