Once upon a time, tag clouds were great navigational tools. In the early days of a blog’s life, it can help readers dig deeper into its content. After a while, however, the tag cloud will get far too big. It will look like shit and could scare readers away from using it. So, at some point, it’s time to get rid of the tag cloud.
Tags are great. The way WordPress works, tags create more pages, which will help you get search engine love. But, abundant tagging will crowd your cloud. So, to maintain the aesthetic, you sacrifice traffic. The compromise is to get rid of the tag cloud. Then, you can tag as much as you want.