It's the only sliver form of inbox messaging available, I'd envision them altering it would get them there. Since the groundwork exists sorta.
They can make simple tabs to have Official messages,friends. Could make it mutual friends only to use to get rid of that issue. A basic friends only gets rid of strangers spamming you.
They can do basic PSA inbox messages warning of ingame impersonation as it is now people still get ironman and vip confused with pmod logos. Can also have a stamp of blah blah this message did not come from official staff. Another game I play does that stamp thing with inbox messages so you know mesages are bs if they don't have the company logo.
Having no form of inbox mail system makes this game horribly dated and I'd hope they'd try to catch up eventually.