Business rates add an extra layer of complexity to an already overcomplicated tax system. They are also unfair, as they vary in arbitrary ways from one property to another. They no doubt also adversely affect the commercial property market, which is probably not a good thing in the current climate.
Their enforcement is also extremely heavy-handed and vindictive.
Putting the equivalent taxation onto corporation tax would also mean that the taxes would only be paid by companies who are making money. In the current system, a company having a bad year might find that their business rates could make the difference between survival and failure.
It would also save huge amounts of bureaucracy. Business have to pay corporation tax anyway, so increasing the rate would add zero extra administrative burden. Scrapping all the bureaucracy behind business rate valuation, collection, enforcement etc, would save a fortune.