To prevent issues like https://github.com/piwik/plugin-CustomDimensions/issues/62

I would say the current way of sanitizing all input is rather an anti pattern and causes lots of bugs.

We need to check if we can remove this behaviour. Problem is that some functionality may not work anymore 100% and we need to make sure that all values are properly escaped when using them to not run into any security issues after removing it. This will be lots of work and need to see if we can manage this in Piwik 4.