I can think of a few things that they might not like. Firstly, terry cotton towels tend to have a bit more bite when removing the dried polish from the surface. Personally, I find MF superior in getting the surface spot free, so I'm willing to sacrafice. MF comes in a variety of weaves and plushness which also varies how much bite you get.
Most importantly, there is a huge variation in quality of MF towels. People can pick a quality 100% cotton bath towel at a department store easily. How many people know how to pick a good MF towel? Then consider that most of the good ones you can purchase are through online sources where you can't touch or feel the towel.
I remember a while back Sal Zaino himself was doing a lot of testing with MF towels, but concluded that he could not endorse then due to the variation in quality.
Companies are starting to make
natural microfiber towels (no polyester) for buffing. They do not really grab like hooks, as the typical MF towel may, but instead they have flat loops like a cotton terry towel.
One such example is the DF towel:
http://www.dftowel.com/
I have a similar product made by a different company, but have yet to try them for buffing. They are however, incredible soft.