I would say yes. It will eliminate long waits and get you better seats. Like if you want to eat inside at Aerial Grotto or water seats at the Blue Bayou.
It probably depends on the time of year that you will be at the parks. During off season, it may not be necessary, but for weekends and peak times, I would recommend it. Unlike WDW, though, there are really aren't too many restaurants that fall into this category, as most of the restaurants at the Disneyland Resort are counter or cafeteria style.