Custom Variables are a very powerful feature of Piwik that lets you track any number of custom parameters to users (visits), their actions (pageviews, events, etc.) and conversions (goals, ecommerce).
By default Piwik lets you track 5 custom variable per visit and 5 custom variable per page.
The goal of this ticket is to add support to let you create and track more than 5 custom variables... so that you are not limited by Piwik and can track any number of data points!
There is definitely a need to increase the number. We should however think of a better way to store custom variables. I know that a new table (e.g. piwik_custom_variables) would be a performance hog so that's not a viable option.