This idea means that important issues are voted on by the MP's who are affected by the changes. A good idea for England could be brought down by MP's in other areas to spite the Government, ie if it was wanted to scrap prescription charges in England then others who already enjoy this benefit may do their best to prevent it. It is called democracy.
Remove the voting rights of MP's sitting in Westminster for votes which do not effect their constituencies. Many parts of the UK have devolved Parliaments which cover many areas, ie the Scottish Parliament deals with things such as health and education. When Bills covering these areas fr England are voted on the Scottish MP's would NOT be allowed to vote. Same applies to other areas and devolved Parliaments, ie Welsh Assembly and the Northern Ireland Assembly.