Yeh a derated climb thrust is for less wear and tear on the engines but it appears to be an 'FMC-only generated' option (for 737 anyway), as theres no published charts or tables from which to determine a suitable derate (clb1 or clb2). Only 'Max Climb N1' tables are provided.
Interestingley enough a derated climb produces a higher total fuel burn from a to b, esp if strong tailwinds exist above 15,000 feet. So if my fuel at destination is going to be a problem (and I have reasonabley strong tailwinds known to be above FL150), Ill use full climb power and max enroute ROC speed until Im in the 'strong tailwind' band. More so if strong headwinds exist below 10,000 ft.
Depending on sector length Ive saved up to 100-150 kg but of course thats at the expense of flight time.