The Israeli (and Italian, for that matter) electoral systems are based on the Triffin Plan, devised by Robert Triffin, the econmist who also was the prime architect of the European Common Market. The idea behind the plan was to let a thousand flowers bloom: giving rise to as many disparate voices as possible. He believed that if all voices were heard a consensus would be reached that would have strong support. Now I knew Bob Triffin well. He was a marvelous human being and a very inclusive person, but he had a very naive views of human nature and no understanding of politics.
I have no doubt that the INTENT of the changed provision was to keep out the Arab and leftist parties. But as others have said this effort may backfire.