I doubt the mangaka have much say about this. It's all on the publishers. In fact, I bet that if there was a self-publishing platform like Amazon's Kindle Direct that actively connected mangaka to top-tier scanslators so they could also sell translated versions on the same platform, they'd fucking jump at it. Because if there is one thing most mangaka care about more than money, it's getting more and more readers. (Not that they don't care about the money - they do - it's just not quite as important.)
The ones that are going purely for profits are the younger Gen-Y executives. The Gen-Xers and Boomers among them that make decisions like that are more about "Japan for Japan only", "Gaijin Go Home", and "Hirohito Did Nothing Wrong" kinda thinking.