Well this is why we want them in the game. They are so flavorful, unique and also, they can progress in the story as a main chapter that isn't one of the main or directly successor chapters. They are their own thing which makes them very cool to a large amount of people.
I seem to remember other chapters pilfering Xenos tech and the Imperiums' own organizations stealing from the Astartes. The Soul Drinkers and the Tech cult if memory serves.
The Blood Ravens aren't "based" off of Thousand Sons. The Thousand Sons sent a portion of their Legion off with a fleet, and as such weren't sucked into the Warp when their Primarch made the deal with Tzeentch. Not all of them succumbed to the flesh-change. And the mutations were psychic mutations caused by rampant use of unprotected psykers, not flaws within the geneseed. The Blood Ravens also found a bunch of records on Kronus alluding to their chapter history, but Thule had them destroyed for whatever reason. The argument could be made that they have a troubled/heretical past. The pre-heresy armor scheme of Thousand Sons is pretty damn similar to Blood Ravens, and they also both (Pre-Heresy) used the same quote "Knowledge is Power". So naturally, the connection is made. And I couldn't remember which legion got fired upon. Can't keep everything retained. It's not a matter of being unreasonable. It's the fact that the Imperium of Man and both the Emperor hated aliens and viewed them as nothing more than something to be eradicated to make way for Humanity. Not only that, but the Ultramarines pretty much worship the Codex as a divine writing by Roboute and it states that Space Marines are meant to be the bulwark of Humanity against aliens, yet they willingly work with them. We digress. I'm not trying to test lore knowledge. Everyone's raking Blood Ravens over the coals while most of the other Chapters do some pretty stupid shit too that conflicts with fluff all the time. And if you can post some fluff regarding Blood Ravens stealing shit from the Imperium and other Chapters and you're not just reading from 1d4chan, then I will stand corrected.
Like how they have relics that ranges its ownership from custodes to space wolves passing through inquisitional stuff? yeah...
I really don't think the wargear in the campaign is considered cannon. Those are simply gameplay elements that added flavor to the campaign. http://wh40k.lexicanum.com/wiki/Blood_Ravens_Armoury#.UqB_xuLcIS4 Most of these are named or forged after important people, but they aren't stolen from the Imperium. Them actually "stealing" relics is just a running joke that people confuse for cannon.
What`s up with people who normally spell great not being able to spell certain words? Cannon = cannon is any piece of artillery that uses gunpowder or other usually explosive-based propellants to launch a projectile Canon= the conceptual material accepted as "official" in a fictional universe's fan base How can you mix up those two? Its such a common mistake and I am baffled. Also horde always becomes hoard. Zombie hoard, for example. On topic, the only real gripe people seem to have with them is the relic stealing, but that was most certainly just a gameplay element, just like Freke said.
Blood Ravens deserve a place in Eternal Crusade if not on start of the game then later on, they are cool chapter yes they have mystic past and many secrets and they are associated with Thousand Sons, but many chapters have secrets.
That and randomly capitalizing letters. But a lot of people aren't here don't speak English as their first language. My friends and I mostly joke around about them stealing shit. We call them Space Gypsies. We all like Blood Ravens though. Maybe they should be released at the same time as Thousand Sons.
