The signatures are basically sent to the customer in a default or base state. If you feel that you need to enable those signatures, then by all means, go ahead. That is why they are there. It is not a 'one size fits all' out of the box database configuration.
You, as a user, have the choice to enable them or disable them. It depends on your environment as to how you wish to implement. Tweak the signatures where you feel they need tweaking.
