As a Roblox developer, it is currently impossible to completely control the message a player receives upon being kicked. This used to be the default behaviour, as is shown on the developer wiki:
But now the kick reason is always displayed as You have been kicked from the game: [Given Reason]
I want to be able to have full control on this kick message without more text being added in by default.
If Roblox is able to address this issue, it would improve my development experience because I like to make sure that my feedback to the client is always precisely as I want it. If I expect to be able to give the player a specific message, I want them to receive that message precisely, and not altered out of my own control.
Another good take on this by @buildthomas would be: