afaik there are expansions way more popular than others, for example HD wasn't a very successful expansion in many ways (by the general opinion at least) compared to Mines of Moria (i'm sure that there are people that do not think that way and that's what this thread it's about).
also, at this point there seems to be a large focus on endgame and stacking old content on top of old content, which strips the whole Massive-Multiplayer Online experience from the early-game & mid-game, which is a big portion of the game (taking in consideration it takes about 500+ hours of gameplay to get to endgame for the average player).
this seems to push the game more towards an Offine & Semi-Online RPG experience (with the exception of World Chat & Auction House) in which you're practically by yourself for months leveling through empty areas and dungeons and this offline/semi-online experience increases with every old expansion that gets stacked upon mid-game content (more empty areas/quests/dungeons).
i guess there's an audience that do not have any problem with the early-game & mid-game content being an online experience mainly for world chat & auction house (or kinships), but virtually empty on the open-world & instance side (dungeons and areas that do not belong to endgame). but that portion of the playerbase it is not the main concern in this thread, but the playerbase that enjoys more an MMO experience rather than semi-online RPG/offline RPG experience, because, as i've mentioned previously, getting to endgame for the first time takes about 500+ hours of empty content (which translates into 4+ months for the average player of not seeing other players but on World Chat, or maybe one player once every few days/weeks).
so, here's the thing.
if players could choose between fixated paths of content instead of being pushed to play 500+ hours of empty zones plus 48 new hours of empty zones for every expansion that becomes outdated and it's placed back on mid-game, the game would be less of an offline RPG experience and more massive-multiplayer online populated experience for popular leveling zones (such as Moria) and also for 3man/6man instances that virtually no one is doing because the gap between level for players increases with each expansion (on Gledden you can only see sometimes only 1 person in the spectrum from 75 to 85 online in the whole server doing Rohan, or 2 persons doing Helm's Deep, one is lv 88 and the other is lv 94).
fixing this content gap will obviously bring more players interested in the game and an MMO experience over an Offline RPG experience.
this squish could take place by giving players fixated paths to go through content, and then selling them as the game experience.
this is just an example of how that could be, not a full representation:
1-10 tutorial/intro (Ered Luin / Shire / Archet / Bree Land)
11-30 standard f2p SoA (Bree Land / Lone Lands / Trollshaws / Misty Mountains / Angmar)
11-30 VIP SoA (North Downs / Evendim / Forochel / Eregion / Angle of Mitheithel)
A Path represents Low mid-game
31-50 A1 Path: Moria / Lothlorien / Southern Mirkwood (free access with VIP)
31-50 A2 Path: Enedwaith / Dunland / Gap of Rohan
31-50 A3 Path: East Rohan (RoR) / West Rohan (HD)
31-50 A4 Path: Base Gondor (Western gondor, Central gondor, Eastern gondor, Old Anórien, Far Anórien, Anórien After-Battle)
then you can sell all "A" Paths as a whole at the web store + a lv 30 free boost (to encourage people creating alts or trying/buying other classes/races). or each "A" path as a separated single path.
B Path represents High mid-game
51-70 B1 Path: North Itilien / The Wastes / Mordor
51-70 B2 Path: Eryn Lasgalen & Dale lands / The Dwarf-holds
51-70 B3 Path: Vales of Anduin / Mordor Besieged & The Morgul Vale / Wells of Langflood
51-70 B4 Path: Elderslade / Azanulbizar / Gundabad
then you sell "B" paths as a whole at the web store + a lv 30 free boost. or each "B" path as a separated single path.
Pre-Endgame
71-80 No Path: Only second last expansion released (so it's still relevant for purchases, as SSG usually does by trying to capitalize on 2nd last expansions)
Endgame
80-90 No Path: Only last expansion released
so, if players purchase full "A" paths & full "B" paths for separated, they get 1 + 1 (2) lv 30 boosts.
and giving players a chance to purchase all A + B paths at once with a discount with something juicy like the 2 previous lv 30 boosts + 1 free VIP month included (which then, they will use for xp boosts while leveling).
or just a more basic (and more cheap) customizable option to purchase just 1 A path (31 to 50) + 1 B path (51 to 70) at once (whatever path A + path B a buyer chooses) to complete one 30 to 70 leveling pathway for a cheaper price than the other 30 to 70 options (full A or full B, or full A+B).
also, giving VIP players 1 free 30 to 50 pathway while being VIP (let's say, Moria to Mirkwood, which might be the most popular) makes VIP more appealing and worth to try before purchasing the whole game.
that's still a ton of content to go through & gives the game a way more populated, alt-friendly, casual-friendly experience that appeals more to a massive multiplayer online audience, over an individual (you've to find a kinship to get help, instead of finding it on the open world), non-alt-friendly, non-casual friendly, semi-online/offline experience (it takes 4+ months of average gameplay and 500 hours of empty zones/dungeons to start playing with other people in teams, unless you find the right kinship).
this way, players who want a more MMO experience and are on the casual/pug side, will choose paths that are more populated (for example Moria), meanwhile, players that want more an Offline experience could choose other paths.
and completitionist/alt-holics will just be encouraged to get the whole game to play all A to B paths with multiple alts.