Tier the individual fights into different difficulties like XI does to an extent - Very Easy, Easy, Normal (Standard), Difficult, Very Difficult. Easier difficulty = reduced mechanics (Like the nerfs we have going into place now in Second Coil, to varying degrees) but leave the numeric checks in place (Add Echo buff into Normal difficulty and below when content ages, leave Difficult and Very Difficult un-nerfed).
Very Easy = 50% Chance for 1 chest to drop
Easy = 1 Chest drop
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Normal = 2 Chest drop (Same as now)
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Difficult = 3 Chest Drop + Expanded loot table (% chance for drops unique to Difficult and Above, could be anything from higher iLvl loot to dye-able Coil gear, something tangible rather than just a title)
Very Difficult (Savage Coil) = 4 Chest Drop + Higher % Expanded Loot Table drops
Lock-outs would stay in place upon clearing an instance, but if you for whatever reason failed to clear you could exit the instance and challenge a different difficulty until you clear.
Now let's examine what this actually does for the player-base.
More casual players now still get to experience the storyline of the various fights, they still have a chance at loot (Albeit, at a slower rate than players who venture into the higher difficulties), and now they get to progress/learn the mechanics of fights at their own pace or in pieces. When they feel ready to try a harder incarnation of the instance, they have that option - or conversely if they feel overwhelmed they have the option to fallback to.
Hardcore players now have an option to go above and beyond the call of duty and attempt Savage Coil (actually makes sense to run as an option for players who are able to clear it because it actually has rewards befitting the higher difficulty of the instance). Nobody has to cry about nerfs anymore with a system like this in place, because the content is actually being tailored for both ends of the playerbase at once.
Very Easy/Easy Difficulty would now (In theory) easily executable with Party-Finder/Pick-up groups and wouldn't require a static. Normal would be basically the way the fights are currently (In most cases, require a static when first released). Difficult would serve as a stepping stone from standard difficulty with amped mechanics, but not quite as extreme as Very Difficult which would be akin to what Savage is now.
No more hardcore players crying about nerfs, no more casual players crying about content being too hard, no more crying about Savage Coil not having any tangible reward. Everyone wins, no?