Another factor in China is that people all ready use WeChat to make payments to each other (http://uk.businessinsider.com/wechats-p2p-usage-is-massive-2...).

Hence, it was a natural progression to allow payments to businesses which is where chatbots came in.

I reckon easier typing would be one of them. From what I've read, predictive text is much better in Chinese, as is voice recognition