As the number of textile mills and other factories in the North increased, so did demand for Southern yeoman farmers, who were mostly self-sufficient, growing vegetables, raising hogs, and making their own household goods.
I'd like to think that the Southerners were okay with the growing number of textile mills, considering the fact that it was also growing their business.
In short, your answer would be: It created a demand for their products.
The demand for cotton, which was produced in the South, increased when the number of textile mills become higher in the Northeast. The Southerners may thought about it positively since there were increased wealth of plantation owners, bankers, and ship owners.
