Preventative dead-wooding
Trees naturally will shed limbs as the are shaded out, injured, diseased, or for other reasons. By no means does dead limbs necessarily indicate poor health. Have a consultation to determine if what you are seeing is typical deadwood or if it is indicative of a more serious issue. Preventative dead-wooding will help thin the canopy as well as reduce likelihood of damage or injury from falling dead limbs!
Tree Risk Mitigation
Dead wooding is also a great form of risk mitigation as large dead branches can be of major harm to a person or property depending on tree species and location.