We can never be sure of what might happen tomorrow, and even the healthiest investors should make plans in case the worst does happen.
This includes leaving a will to the family so that the estate is passed on, and this includes any property that the investors own, including in Thailand. You should also ensure that a will is made in Thailand as well as in your home country, to help ensure a transaction that is as smooth as possible.
Even if a will in your own country does meet with the Thai law, it can still be cumbersome for your family to receive the property. The last thing your family want at such time is to have to deal with the language barrier, trying to understand Thai law, and especially any disputes that might occur.