They haven't done anything in Indonesia since August, the JW Marriott, with 90 percent Indonesian Muslim casualities.
That has apparently caused JI to rethink its approach (just as AQ now is in Iraq).
In any case the hotels and malls in Jakarta are pretty much buttoned-up with security. You cannot get a car to the front of any major hotel or mall without running a gauntlet of Jersey barriers, guards equipped with batons, knives, and full-auto weapons, being wanded, and having your trunk searched some distance from the front entrance. It's an amazingly efficient and thorough process.
The U.S. Embassy in Jakarta is secured like Ft. Knox, there's zero chance for them to get close enough to do any damage.
As a side not, when they nabbed the JI's Hambali in Thailand last September, it was revealed he wanted to bomb Khao San Road in Bangkok, a backpacker spot very much like Bali. But again, they would have injured a lot of Thais (making yet another enemy), in addition to Brits, French, Swedes, etc. with very few Americans (Americans tend not to be big international travelers, I would guess 10 percent on KSR at best). In any event the Thai military police put up barriers on each end of Khao San Road as soon as JI's plans become known, so no vehicular traffic there anymore (scratch another marginal target).
With every single place that these psycho Muslims target, they have the certain potential of bringing even more disgust and wrath upon themselves than anything they could possibly gain.
And should they choose an American domestic target, they'll have to calculate the inevitable repercussions against all Muslims everywhere, particularly here in the States but also in all Western countries (e.g., France, Spain, Belgium, Germany), not to mention parts of SE Asia, India, and elsewhere.