... and Farrell was the only one who made a stink about renewing.
Fans sometimes forget that to the performers Star Trek is just a professional acting job. At the end of her contract Farrell had a chance to make a lateral move over to a comedy series starring Ted Danson and have a better billing position with higher pay. To turn that down for a single additional year on DS9 would have made no sense career wise. She did four years on Becker, while many of her fellow actors from DS9 worked only occasional.
Can you really fault her decision?