Having a will is important for everyone not just for those who have lots of money. In Scots law there is a different procedure for people who have a will (testate) and those who die without a will (intestate).
The law assumes that your estate will go a certain way on your death and if you do not have a will then that is what happens. However, the procedures are more complex for an intestate estate.
If you have a will you can control where your estate is to go on your death and the proceedures are simpler, quicker and cheeper. Therefore for your loved ones left behind, having a will lets them deal with your estate with less hassle.