Flagging just like self voting is a built in part of steemit. I've seen many $100 posts that create less value for Steemit than some $10 posts.
While the system isn't perfect flagging is the only tool that we currently have to prevent abuse on the platform and to equally distribute rewards. People are just too sensitive and need to get over themselves.
With that said I think abuse needs to be the focus for flags more so than "over valued" posts. "Over valued" posts are based on opinion while abuse is more apparent.
which is why we need to have a public daily list of rewards and flags per user to double check if such things happen