Really good question. If a college that you are interested has a requirement, then I would heed their words and do what they say. You can call and ask the admission department what their policy is, but I would not ignore what they say is a requirement and hope that they don't throw away your application. There is a reason that colleges have requirement and it isn't for laughs, they have requirements so as to attract the student body that they want. Some colleges require ACT w/ writing while other colleges do not care about whether or not you submit an ACT w/ writing. Every college is different so you should check every one of their websites and call their admission department to be sure. If they, meaning the admissions department, tells you that the writing is required, DON'T ignore them. Having an application thrown out because you didn't follow all the directions is not fun at all.
I hope this helps and I wish you the best of luck.