Understanding governments tendency to over govern, the idea that a simple majority seems an excellent idea. Requiring a two thirds majority to pass a law would certainly temper any law makers capacity.
I remember as a child reading a novel which was based on a military coup in Great Britain. Parliament was retained. What I remember most and have always thought a good idea was the new dictators proposal that a new law passed by parliament woukd require a majority of 66% while to repeal one only required 50%.