That's because they've increasingly been trying to idiot-proof the codecies by including even the most redundant information, such as anything that can be found in the main rulebook. I don't know if you noticed, but the rules for basic close combat weapons appear in Codex: Orks purely to clarify that there's no distinction between a choppa and a close combat weapon anymore.
An Emperor's Champion may only have two attacks on his profile, but consider the following: He's armed with the Black Sword and a bolt pistol, so he's double-armed. That's three attacks. If he charges, he gets four. He's WS6 and S6 with that Black Sword, so as a balance issue, he isn't able to whip out six attacks on the charge like a Marshal or Chaplain can. He's really intended to kill enemy independent characters in one stroke, too, and to be fair, most of them only have two wounds-- three attacks which usually hit on 3's and wound on 2's should be quite sufficient most of the time to neutralize enemy characters.