information usually travels UP the chain of command, scouts report to their superiors, they report to theirs, etc. till finally it gets to you. so it makes sense that Preston (who I would assume holds the rank of Colonel along with Shaw) would end up giving you the information.
though at this point the general would usually delegate back down the chain of command what needs to be done instead of taking care of it themselves.
personal things I would like to see:
-the ability to delegate the various settlement problems to the minutemen with varied chance of success based on how big they are and there gear (gear leads into next part)
-gear, the ability to invest in the minutemen to increase there effectiveness (better weapons and armor, they are all after wearing the minutement outfit so could wear full armor over it, and the possibility of more of them)
-there overall strength would be based on # of settlements (up to a cap) their gear (based on investments up to a cap) and the amount of artillery you have at various settlements (up to a cap)
because I would love nothing more then to delegate all those radiant quests I can never seem to be rid of.