Major League Soccer wants to expand. They have made no apologies for stating as such. Commissioner Don Garber recognises the growing market for soccer — and for his league specifically — in North America and he wants to make the most of it.
It makes sense. The financial motivations are only increasing, there is always a desire to grow your league into one that can rival the elite North American sports, and to do that, you must tap into large markets. This is why there have been recent expansions into Nashville, Cincinnati, Austin, and Miami.