Plus how would you control each batteries individual charge? Some people might run 4 batteries where you would want at least 1A each or 4A total charging power. Some people might only use 1 battery in the light. If you put all 4A to one battery it’s too much. So it is very difficult to control.
A built in charger would almost assuredly require a sealed battery back. People really don’t like battery packs.
This conversation has nothing to do with the current Q8. The future Q8 v1.5 thread is the place to talk about it. Q8 v1.5 here.