Sitecore.Layouts.RenderingSettings.Parameters should be deprecated, and a new collection ParametersDictionary should be added to that class. This would be synonymous with the property Web.UI.WebControl.ParametersDictionary.
Adding this collection would make it more reliable to retrieve individual Parameters from the RenderingSettings. Currently, I have code in my back-end that manually url decodes and then splits the string returned by Parameters. This is inappropriate. I should be able to access an API, and get back exactly what was entered into the Rendering (additional Parameters) without having to worry about how it is being stored.
PS: Sitecore, internally you can cross-reference wish # 104675