Last night on Twitter attention was drawn to the discovery of a pile of reportedly badly forged Turkish passports and the possible Uighur links, not to terrorism, but enabling refugees to travel.
Not sure what this comment means, but this is clearly terrorism. The motivation behind the attack still remains unknown to the media. However, even media reporting points out that two apartments have been raided, and both contained bomb making materials indicating the potential for several additional attacks.

The Chinese claimed the Uighurs Thailand sent back were enroute to Syria to join ISIL, but apparently provided no evidence. However, some Uighers have been associated with Al-Qaeda and other extremist groups in Afghanistan, so while we can't trust China, their claim isn't out of the realm of the possible.

If the attack is a revenge attack due to the forced repatriation of the Uighurs or the mistreatment of the Rohingans trying to immigrate from Burma it would highlight the risks associated with the current global migration crisis. Much of it driven by the current crisis in Syria and Iraq. Perhaps it is being viewed as a crisis due to the coinciding with the economic crisis. Resulting in a right wing backlash in parts of Europe and the U.S. (due to Latin American migrants). Perhaps it is due to the perceived threat a large number of foreigners with very different cultures present to the countries taking on tens of thousands of migrants? Regardless, migration in many parts of the world ranging from Australia, Thailand, Europe, and the U.S. is now seen as a crisis that will likely result in more violence against migrants, and the raise the potential for revenge attacks. I don't see this problem going away anytime soon.