Tennis in LA is an epic fail. Few crowds, little interest.
WTA are building a presence in Asia, thus it's fitting to have a mandatory tournament here
The Asian HQ is in Beijing
The Chinese crowd would probably be more present, with better ticket sales than LA
It's a good way to raise awareness of tennis in Asia, more specifically China, rather than trying to revive it in a city which doesn't give half a damn about tennis, especially women's tennis.
It's a new venture. If it bombs, then they'll learn from their mistake, but it could be a success.