As a writer I do too. There are many issues with the scheme, primarily around the elements of 'writing' which are technically essential to making a living (teaching, talks etc), but not covered in the requirement that income be primarily from writing. That said, it shouldn't be an excuse for very wealthy people to use Ireland as a tax haven. We already get enough of that with the corporate tax rate.
I agree with the cap, as people earning more than 50k p.a. from their arts don't need it.