not 2000 why the frell does it say 2000? is it because of the millennium expansion?

that shouldn't be as the game came out in I think round may - june in 1999

According to the steam page it came out "28 March, 2000", although wikipedia seems to list it as "30 April, 1999", so no clue on the name. Maybe it's referring to the release date of the gold edition?. Also this is an update to the original for modern systems and online features, originally came out on steam back in 2010 I believe.

I believe this is a HD re-release of the Gold Edition, which came out in 2000 if I am not mistaken, that is why the Gold Edition maps and weapons like the Skeeter Launcher are in this game.

On a side note, may I ask why this is bothersome to you?

Because 2000 arguably sounds cooler.

Yup, it's Gold Edition exactly (well, with a few extra bugs). If they really wanted to release the game in its most updated form, they would've included the 15 custom maps that were released by Rebellion from downloadable 7 packs. As it stands, you still have to dig around to get em.