Why Veto right accepted in UN?

There are five veto wielding countries in the UN: Russia, China, France, UK and USA. They were the big winners of the second world war and they effectively sorted out the rules of the UN to suit themselves. They are the only permanent members of the UN Security Council. None wanted to have the UN tell them what to do, so they agreed that this could never happen.

Now that the world has changed, none really want to give up this power, although France and the UK both say they support UN reform that would bring more countries into the Permanent Members club (such as India, Brazil and South Africa and others). Other UN members can't change the veto rights of the permanent five, without risking the use of the veto they want to abolish.