Messaging is of course allowed. But people should have ownership and control of their own attention span. For a person who has a thousand people seeking their attention every day, that person should be able to filter out those who weren't willing to pay for their attention. That same person could lower their price to allow access to their attention if they personally want to make it more accessible so that they can better the community as you say.
But that should be a choice.
RE: Steem Improvement Proposal, Minimum threshold for being notified of transactions / memo messaging.