MicoSelva I don't think the current list is representative of a "niche site that hates everything released after 2000", because that's not what the RPG Codex is.
Here's my analysis of the five "intellectual currents" of today's RPG Codex:
1) Black Isle-ism. Probably the most important current, and the founding philosophy of this site. "Black Isle-style" means any game that belongs to the lineage of Planescape: Torment, Fallout and Arcanum. RPGs with lots of scripted choice and consequence, novel storylines and interesting, non-generic settings. This current manifests as a sometimes unseemly fanboyism for Black Isle successor companies - Troika (especially), Obsidian (to a lesser extent) and, if things go well, inXile.
2) Nostalgic oldfag-ism. This is a general yearning for older forms of RPGs. In particular, not just Black Isle-style RPGs but also older ones. Blobbers, dungeon crawlers, Gold Box, Wizardry & Ultima, etc. Posters like mondblut and Sceptic represent this current well.
3) Anti-popamole-ism. This is a harsh dislike for various modern trends in RPGs, including consolization, romances, quest arrows, and the like, and also for the companies that most exemplify those trends - post-NWN Bioware and post-Morrowind Bethesda.
4) Eurodev underdog-ism. A relatively high tolerance for games made by underdog RPG developers, especially European ones, and an appreciation for their unique "quirky" natures. That means Larian, Piranha Bytes, CD Projekt, etc. This current isn't as strong as it used to be, since many of these companies have proven to be fairly popamole themselves, with the notable exception of Larian.
5) Tactical combatfag-ism. Obviously, this current represents the people on the Codex who really like tactical combat. The JA2 fans who want JA2 combat in every RPG, and the people who obsess over the details of combat systems. This current was deemed important enough to get its own RPG Codex spinoff site, Tacticular Cancer, with mixed results.
I've found that most games that people consider "Codexian" fit well with one or more of the above. It seems you're thinking only of #2.