You should not assume your spouse will have total control of your finances if you become incapacitated. Although your spouse has some rights over property you own together, like joint bank accounts, he or she is restricted from doing certain things with that property. For example, generally both spouses must consent in writing in order to sell jointly-owned property. Because an incapacitated spouse cannot consent, any such transaction would be delayed or prevented.
If you own property by yourself, your spouse has no legal right to sell or manage that property without a power of attorney. A power of attorney that gives rights to a spouse often makes transactions easier and more cost-effective. A LegalZoom Power of Attorney lets you provide your spouse with the general and specific powers you choose.