In addition to tools, these kits contain replacements for parts that have a tendency to wear out over time, especially in case of laser printer maintenance. Collectively, they also cost less and save you the headache of waiting for a technician if your printer suddenly decides to die while printing an important document.
Proper maintenance, along with a handy maintenance kit when you need it, ensures less stress when you have important work to do. Not only is it a very reliable well-maintained printer, it also produces high-quality prints for a long, long time.