You're right, I was painting with a bit of a broad stroke on this (specifically referring to a particular thread that keeps popping up on the first page in this forum), and I am by no means saying the current system is anywhere near perfect.
Currently there are a few places where a skill gap could be filled in with more middle-difficulties of content, and I think that'd be interesting to see.
Current scale, ascending in difficulty:
- Lv50/60/70 Dungeons (and lv80 dungeons when Expert eventually evolves)
- "Expert" Dungeons
- Leveling Dungeons
- Alliance Raids (other than CT, which doesn't even belong on the scale)
- "Hard" Trials / Normal Raids
- EX Trials
- Savage
- Ultimate
Up to about EX trials, I think the skill build is pretty well designed and flowing. There is a jump between EX Trials and Savage raids, however, and I'd be all for a difficulty level between the two. In terms of difficulty, I would view EX trials as about on par with 'normal' raids in WoW, and Savage as about on par with late-heroic/early-mythic in WoW...and I'd be all for a 'heroic' equivalent difficulty between for players who want more of a challenge than EX but aren't yet ready for savage. This could also fit well into gearing (for example, the 'heroic' equivalent Eden could drop 460 gear, whereas savage currently drops 470).
(I can't speak as to the jump, if any, from Savage to Ultimate, as I have not yet gotten there [but I will, eventually].)
That said, even this idea does have a problem, though. From my experience in WoW, 'normal' raids became mandatory when progging heroic, because the gear upgrades were still worthwhile, and heroic was still mandatory while progging mythic, for the same reason. (Actually, it was even worse still, with Mythic+ dungeons also being mandatory for some mythic raid prog groups [like the one I left when I quit WoW {again} back in December].) Of course, I believe we have some great people behind the development of this game, and they could probably figure something out.