Done properly, the main advantage is to bypass the need to probate your estate in each place you own a timeshare.
Should you live in NY and pass away, with timeshares in Florida, Pennsylvania, and Virginia for example, your estate would first need to be started with the NY Surrogates (Probate) court. Then your executor/Executrix would need to petition the Probate Courts of each of the three states for permission to dispose of your assets in each state.
If an attorney is used in each location, that will add many thousands of dollars of expenses to the costs of the estate.
If the heir's name is already on the deed with rights of surviviorship, all that is needed is a copy of your death certificate and then only when the timeshare is sold or someday retitled by your heir(s). Thus saving thousands.
This assumes that the deed is properly worded to include rights of survivorship and that the deed is worded properly as to ownership type. For example, most states do not allow joint tenants to be modified after the original purchase.
Estate planning is not a simple, do-it-yourself thing in most cases. That's why the pros are best used. However, I'm biased, my company does many of these transactions, but the heirs will not have unpleasant surprises.
The alternative is to just live forever...
PS. In addition to preparing the new deed, it does need to be reorded and the resort notified. Most resorts waive their transfer fees in such cases. Also real property transfer taxes are usually exempted in such a transaction. This helps keep the costs down.