Yes. While your spouse may be protected in the event of your death because they can access and use your joint assets, you should still plan for what happens after both you and your spouse pass away.
More importantly, while joint ownership may give your spouse the ability to access joint accounts, that does not necessarily mean that you have complete control over them.
Consider, for example, joint ownership of your home. If your spouse becomes incapacitated for any reason (such as permanent disability, Alzheimer’, etc.) and no longer has the contractual capacity, they would no longer have the power to sell or transfer any interest in the home.
This then inhibits your ability to sell and move your home and refinance it (such as a reverse mortgage). Without a financial power of attorney in place, your only recourse may be to seek the judicial appointment of a conservator for your spouse.
Appointment of a conservator is a judicial process that can take a month or longer and must involve an in-person hearing. Furthermore, a conservatorship is an ongoing proceeding requiring yearly reports and accountings to the Court. This adds much unwanted time and complexity to a process that a power of attorney could have streamlined.