The idea that incorporated business owners only pay 15% is a total myth.   Income coming into an incorporated business is taxed lower initially, but when it is withdrawn from the business it is taxed a second time.  So unless you don't draw a salary or dividend, you get taxed the same as anyone else.  The corporate tax system does allow some flexibility which is highly appropriate for the self employed. I think people who are for this proposal do not fully appreciate how self employed people manage their finances.  Self employed people do not get a regular paycheck in many cases.  Some years they make more than other years.  They have to finance their own maternity and sick leave. 
 The corporate rules are there because they fit with the realities of self employment.  I think the government's assertion that self employed are cheating on taxes or taking advantage of loopholes is not just wrong, its offensive and amounts to spreading of dangerous misinformation.