Every support bonus, even alien weapons get announced to both sides. I was getting max nano a couple times per round last night and most low levels were always deer in headlights and some started rage quiting after my second max nano, since they clearly didn't realize what was going on and probably just thought I was some A-hole hacker.
Not just for bragging rights but to strike fear into the other team

plus it would help to let your teammates know that they got a max nano teammate active and might adjust there tactics to add even more to the advantage. Obviously I play with randoms mostly, since this wouldn't matter if you mic'ed up and or in a squad, but for the rest of us it would be appropriate to have it announced.
I felt kind of dissapointed the first time I ever got the max nano at release, I was just waiting to hear "Alright!, one of our teammates maxed out his suit, show them no mercy!!!" But nada

. Only "your maxed suit is good to go" sort of anticlimactic and your the only one who can hear it.