Each expansion to date (boxed anyway) has brought about new content, and old fixes! Any Expansion will bring its share of new Enemies to take down, New areas to Explore, New monster Families to Defeat, New Armors to Obtain, and new Endgame Activities. Let me name a few!
RoTZ: New jobs, Added Multiple Brand-new Zones, Sky, Gods, Hecatomb/Shura/koenig, Sky gear (Kirin's Osode Set). Antica, Gigas. Absolutely BEAUTIFUL areas like Zi'tah. Expansive zones still in our memories today.
CoP: Added Multiple Brand-new Zones, Sea, Torques, Luminians, Absolute Virtue, Corses, Antlions, Sea-Capes. Added (AV) one of the most infamous monsters to date.
ToAU: New jobs, Added another Continent, Mamool Ja, Wamoura/Campa, Trolls, Lamia, Qutrub, Imps(Merit mobs!), Colibri, Salvage, Einherjar, Revolutionized Exp parties. the ZNM System with another Infamous Monster (PW).
WoTG: New jobs, Added 3 New Zones, Reused most, Slugs, Campaign, Ixion/SandwormBattlefields, Ruszor, Amphiter's(w/e!), Campaign-Armor, Sandworm-BF-Armor, Walk of Echoes. It was lesser of the expansion, But still managed to add a lot of content.
Every expansion too date has completely changed certain Aspects of the game rather it be Exp, How we play(New jobs), or certain NMs, and all while these were released, Old Problems were still fixed. This game has still come a VERY long way. There might be some old problems (I can't name any?), but as history has shown us, They can release expansions and Fix bugs, Problems, and still release meaningful and Enjoyable Content.
As Gwyn Said, We've all been Teased with talk about all these Wonderful worlds, "The Far East", the "Mithran Homeworld", etc, "The Western World". We're continually teased about these places. Players want to explore more. The above areas could very well have contained the Voidwatch System, instead of re-using places like Ranguemount Pass, Dangruf Wadi, and i can assume Horutoto Ruins.
We all want new exciting Content, but we want new exciting places to explore that content. Even if that thrill only lasts a short period, it would be worth it. I still haven't explored some places of ToAU.
We all also want fixes to old content as well, But again, As history has proven to us, They can release Grand expansions with new zones and still give us meaningful content and much needed fixes. Even the "old dev team" who usually fell on "PS2 Limitation" or "I can't do let you do that Starfox" managed to Release New expansions, and fix a lot of problems.
I'm sorry If i come off as greedy when i say, I want new Challenges yes, But i also want new places to Explore and experience these challenges. History has shown us it can be done, and that regardless of rather an expansion is coming out or not, Old problems will be fixed, and some will be overlooked. It happens.
I feel if we truly let the dev team know we will all fully support a new expansion, new zones, New areas, new mobs, new challenges... that maybe, just maybe, Some day down the line We'll be standing next to Tenzen in the Far East.
Or meeting with a Mithran Tribe leader.
Edit: Made it nicer
Edit2: Clearereded my points. I Hope you understand what I'm trying to convey.
Edit3: Fixed Spelling Errors, I'm 99% positive my Keyboard is Fking with me <________<