I speak British English and it's more a matter of register for me. If I'm writing something formal I'll use the subjunctive, if I'm talking to friends I'll just

I speak British English and it's more a matter of register for me. If I'm writing something formal I'll use the subjunctive, if I'm talking to friends I'll just stick with the indicative. If I saw someone write "it is necessary that he goes" in a paper it would stick out as strange to me, likewise if I heard someone say "it is necessary that he go" it would sound overly formal and a bit stilted. So really, you can use either and be understood perfectly well. It only seems to annoy prescriptivists, and I would say one has a moral obligation to annoy prescriptivists anyway.