Can you maybe enlighten me about what problem c-s-v solves that would have me start to use it?

Your explicit ‘setq’ calls are perfectly fine as long as the variables you set do not have a setting function

assigned to them. However, if they do have setter functions, then the behaviour will not be correct.

It has been suggested that you manually look at the ‘defcustom’ definitions of the variables so that

you know which ones doesn't work with ‘setq’.

The only reason people can get away with not doing this is because there are so few custom variables

that use setter functions.