It's a great way of getting useful information out to your clients where they can access them as and when required. Also helps you not have to repeat basic and most asked questions each time. If you have a KB article on the subject, simply direct your visitors to it and save precious time, energy and resources which can be diverted elsewhere.
Use the KISS method.... while many knowledge based support files have a wealth of information, keeping it simple and concise is a challenge for most webmaster as some get really into the technology part and miss the simple aspect of why or what.
We have a rating system, if it scores high in use its doing its job by keeping support tickets down. This improves production and lowers the use of added resources.
Yes i do need knowledgebase a lot. My customers really use it a lot. Some topics if properly described are very useful for people. They know more so they know how to operate tool, avoid problems etc. and so us providers have less job in answering tickets because part of information is already in knowledge base and customer usualy gets familiar with it.