This is Dometic's list of benefits of limiting the startup current:
Reduces strain on the power source
Reduces brown-out effects at compressor start-up
May enable an inverter to power the air conditioner
May eliminate the need to upgrade the generator
Fault-code LED provides troubleshooting assistance
Easier wiring with new termination block
Inexpensive, small, and lightweight
In addition, they say of the reduced startup current "it’s also LESS STRESSFUL for the compressor itself" (caps added by me).
This type of device is slowly being made mandatory by municipalities and power companies to reduce the startup current disruption of the distribution system.
Dometic brochure here
http://www.dometic.com/QBankFiles3/EPiServer/Dometic/US/Specification-Sheets/Marine/Air-Conditioning-Accessories/3486-SmartStart-II-specsheet-Web_29856.pdf