What you're talking about isn't risk, what you're talking about is safety. MOST studios are making complex darker films these days which are more readily successful, which you are calling is risk taking. In an an age where lighter films aren't making as much money, you're saying a studio staying family friendly isn't risky. So making a dark film like every other studio - risky. Making a family friendly film not like every other studio and aren't doing as well - not risky. Got it.
Opinions don't really fall into risk taking or not risk taking. Just because you didn't like something doesn't make it not risk taking. You're saying John Carter looking like a joke to you as defining why it isn't risky. While I'm saying it's risky because you won't see any studio these days taking a risk on a film of the like which isn't trek or wars.
Pacific Rim will either show that audiences aren't hip on giant robot movies like Transformers, or it will show that giant robots are in. You can clearly and more readily see this in how audiences reacted to Battleship. key point being the studio's decision there as to why is clearly transparent - trying to cash in on Transformers. I'm not saying Del Torro saw it that way, as a cash in, but the studio did. Transformers 1 was risky - pacific rim is not.