AFAIK: Kernel-power-settings is mainly scripts and a command line-tool used to ease maintenance of multiple kernel configurations. It has about 8 built-in configs, and the kernel-config tool that lets you load configs or change them on the fly. You can do everything this package does by editing /etc/pmconfig and rebooting, or by touching /dev or /sys files. The tool just makes it a little easier for us humans. Do you need it? No. Does it affect anything if it's there (or not)? Not really. It exists only to make user configuration easier.