Pretty simply, the removal of the message was an unnecessary tweak which only served to make round ends less satisfying and more confusing. The reasoning by Apop for the change was basically "If we make it less satisfying for both sides to win, they won't tryhard as much and we'll get more roleplay", however in the years since then this has been proven wrong, since both sides have tryharded just as much since then, and there hasn't been any increase in roleplay. Besides, it's universally recognized when one side wins at the end of the round, the only thing the lack of the "xeno/marine major" message does is make everyone kind of confused (there's usually someone asking "who won?" after the round ends), and especially confused if it's a marine/xeno minor since to them the round just abruptly ends without much of a conclusion, with the xeno/marine minor message back it'd give a more conclusive end to the round.
I don't care if we're bringing back the "God has a hard-on for marines!" marine major sound clip or the "Game over man, game over!" xeno major one or not, but when talking about it everyone seems to agree they at least want the "xeno/marine major/minor" messages back.