aisaacs wrote:
doesn't it make it more fun when the list are bigger with more variety
The design philosophy for Epic is what Jervis handed down. Instead of one big, all-encompassing list, the goal is lots of army lists geared to different flavors and styles. More focus makes the army lists easier to develop and balance (in theory, anyway).
Players can pick the list that best fits the style they want to play. So, if you want a classic Ork list, you can use the core/Ghazkull list. If you want a fast, Evil-Sunz style list, you use the Speed Freeks.
And you should feel free to use the same minis, regardless of the nominal title of the army list. The titles are basically just for a bit of background feel. The "Blood Angels" list can really be considered just "Space Marines With an Assault Focused Strategy" but that's no fun as a list name. So, as an example, I'm building a second SM army with lots of bikes and speeders that I will field as either White Scars or Dark Angels/Ravenwing, depending on what I want to play that day.
More specific to Chaos, the Black Legion is sort of the neutral, all-purpose CSM list. Red Corsairs is written to represent more recently-turned Marines, but it will work for any less-corrupted force or for a warband that has captured a lot of more recent SM technology. The cult legions are all represented. It's a bit more of a stretch, but you could use them to represent certain styles of play, even if you don't want to play the actual cult. The World Eaters or the Khorne Renegades list could be "generic berzerker chaos marines" or the Emperor's Children "speed cult chaos marines".