When designing a report, one can choose between 3 options: Go to report, Go to bookmark and Go to URL.
The most convenient is Go to report but it as a performance degradation defect (keeping report execution history increases report generation time at every hit). See this connect entry: https://connect.microsoft.com/SQLServer/feedback/details/833306/easy-to-reproduce-significant-ssrs-performance-degradation-when-using-go-to-report-actions
Go to URL was probably designed to link to some non-SSRS content. But it can also be used to link to a report (even the current one) with a different set of parameters values. It has the advantage of flushing the report history (from the View State) and so avoid the performance degradation issue.
Problem is that it uses an HTTP GET instead of an HTTP POST so the length is limited to around 2000 characters.
Even with some ASP.Net MVC applications, it is frequent to reach this limit while redirecting users to a view with a very specific context (Year, Month, Department, Job title etc.).
Now that RSViewerPage has been fixed (KB 2913206) to accept HTTP POST, it would be consistent to remove this limitation and use HTTP POST all the time for Go to url actions.
Small change, big impact.