Dying without a will means you have no control over your estate, and it has to go through the court process, passing on to your heirs in accordance with state laws. Even with a will, it can take time and money to show that the will is valid and start to move assets around -- especially if the heirs have any sort of dispute about the validity of the document. Though a will lays out some of your wishes, it does not really give you control.
As a result, more and more people are turning to trusts. They give greater control, making it so that the estate plan accurately reflects what the deceased wanted and making the process simpler for the heirs.