It’s not a simple request, the same request was denied to the most influential elf in existence, three times. When Gimli asked for it while being humble, she gave him three at the same time. There was also huge stigma and conflict between the races, and the fact that he even tried / dared to ask was huge, and her giving it to him means dwarves and elves can work out their differences after all

“I personally think the hair has a part to play, but for good or for ill?”-Gandalf