A little bit of prefacing: first, a good post from the OP. Second, a few good posts here, but Malzian's post stands out quite well to me. Third, I used to be a raider, and pretty hardcore at that with WoW raiding Heroic before they changed it to Mythic, but I can't currently commit to any organized runs in this game. The whole vitriol between raider and non-raider on these boards is rather reminiscent, but feels like it's on a different level of friction than what I'm used to. Given how I started, how I progressed, and how I currently am as an MMO gamer, I feel like I can see both sides of this. If I may delve deeper into the current situation from my perspective.
The reasons for me to raid is to experience great encounters, the challenge of beating them, the camaraderie that comes with it, and gear. Even at current, I strive to perform as best as possible and gear as much as I can, because that's how I like to play. Story, despite my love for good narrative, plays zero part in raids. The only thing I can really comment on it is that the story for Alexander, in my eyes, is bland at best, but given this game is story driven, it is a good move to make it more accessible, and I don't think it should be so out of reach here. With that said, I've never taken part in Savage or any raiding here, so this is the view of an outsider with a heavy raiding background that is currently, what others would call, casual.
From my limited perspective and with a bit of projection of how I would feel about the current situation, it sounds like the encounters aren't quite different enough to add some zing to the bosses. If I were presently doing said content, I may find myself wishing there were more substance. While not all heroic bosses in WoW had added terribly new stuff, there was just enough that were different to make it a more interesting raid, be it entirely new mechanics, new phases, or tweaking mechanics to make you think differently about how you do it. If it were Fight A with more sparkles, then I can see myself being bored.
Another thing I can only observe is that having only one raid (if you don't include trials) to do over an over can be a pain. Bolding for emphasis before I start my giant ass comparison, I get that SE's strength isn't raid design and raiding isn't their breadwinner here, but not having a good menu to choose from can stifle growth in it and leave people languishing. My raiding started in BC, but up to me quitting after Cata, I've had a number of raids to do, plus a lot more than two heroic instances to run. Perhaps as far as raid types go currently here VS what I did in WoW, I can best compare a two trial-one raid setting to WotLK (didn't raid Vanilla, so no applicable views there) since on release, it did only have one multiple-boss raid, but here's what was on the table: Naxxramas (10/25 man multiple boss), Eye of Eternity (10/25 single boss), Obsidian Sanctum (10/25 single boss with token trash packs, and with the option of making it harder by leaving mini bosses alive), and Vault of Archavon (10/25 initially single boss, more were added later, though note that it was in a PvP zone, which affected what faction got to do it at any given time). All of that, plus heroic instances, at end game. The only time this has failed me really is WoD, where there was only one raid to do, and that didn't keep me entertained for long.
Would having more than one raid alleviate the problem? Perhaps, but maybe it would only delay or prolong the problem. What about difficulty levels? Without repeating my first thought, hypothetically speaking, if I had a lot more free time, I would do Savage and possibly find the difficulty fine, because I'm strange and love beating my head against a wall. What if I had only a little more time than I do now, or if I wasn't busying myself with other aspects of the game? I wouldn't have the ability to commit to Savage, but I find "Normal" to not be normal at all, I find it easy, but considering the nomenclature in the game, it seems to go Normal, Hard, Extreme, Savage. How about adding a third difficulty in between? Not a cakewalk, but not putting yourself through a meatgrinder. The suggestion has come up before (and I think I saw it here too). I've also seen suggestions for more fluff (items, mounts, glamour, titles) to be added to Savage, but that feels more like a band-aid.
Now tying in my first point, a third difficulty with differences in encounters at the different difficulties could be a good solution. I still think more than one raid on top of those two points could help, but raids to take time and resources. So easily said, maybe not so easily done with the latter, but the first two, I would say is more feasible.
That's my view of the whole situation and what my opinions are on what to do with it. Varied content, possibly only at the price of slightly longer development times.