Personally, I think they should stick with the normal and brutal versions. Have the normal version that gets nerfed over time (though still require some effort. While within the current set of content, a raid shouldn't ever be just handed out). Once the next expansion hits and makes those raids obsolete, they should be gutted for difficulty ('cause honestly, why would anyone run them anymore except for glamour/furnishing items?). People that complete it first still get the reward of getting the gear and the story a good 3-6 months before anyone else, and gets them geared for Brutal.

The Brutal version should stay the same forever AND drop special versions of the gear. It wouldn't have any extra stats (or maybe a very small bump, like a HQ version of a gear), but would have extra graphic enhancements like particle effects or maybe be dyeable, in order to make those people stand out (along with extra titles they already get). Maybe make the furnishing mat drop(s) make a version of the furnishing that's extra glowy, too (like the difference between HM and EX Primal furnishings).

I do agree that people that can beat Coil should get rewarded, but as long as they keep the raid tied to important story elements, everyone should be able to have opportunity to complete it -eventually-, even if they're only got a mediocre skill level. However, there always should be a version that will be a challenging version that gives special rewards to those that manage to complete it for those that play Coil for the challenge, and the loot is just a means to the end. I'd even go so far as to put an iLv cap on the Brutal versions, just so they STAY hard, no matter how overgeared you get.

Now in the future, if they made raids have no story elements beyond the lore that it establishes before you go in it (oh hey, this hole in the ground has a long lost Allgean ruin that we'll explain the lore of in a cutscene before you go in. Now go loot it. You know, like most 4 man dungeons in the game.), I wouldn't care less about how hard it stays.