If it costs too much resources, then those resources are just not good enough. Much better games have been made with much less resources.
Seriously, when i make suggestions, i don't keep to the Bethesda resource managment plan.
Very well.
I want all of Nirn, all of the 16 Oblivion realms, all of the 8 plane(t)s of the Aedra to be fleshed out to the level of detail of Morrowind, yet to the scale of Daggerfall.
I want completely dynamic relationships with characters, of the level of a Bioware RPG, but extending to every single NPC in the game, of which I want 800+ like Oblivion and Morrowind.
I want a dialogue system with the same amount of Morrowind's topics, but with a completely unique answer for every NPC, and it all has to be voiced with 3 different voice variations per race/gender permutation.
I want to play as any race mentioned in the game; that means Sloads, Ka'po'tun, Tsaesci, Tang Mo, Kamal, Maormer, Imga, Falmer, Dremora, Xivali, Mazken, Aureal, Yokudan, Khajiit and Argonian sub-races, etc.
I want all those above-mentioned races, along with the stock ten races, to be triple the quality that they were present in Oblivion, x3 texture sizes, x3 poly counts, x3 face-generator options, x3 age overlay textures, complete with scar options, tattoo options, and x3 the eye colors and hairstyles.
I want to be able to court and marry anyone in the game, and I want unique courting dialogue and events for each person; I also want the freedom to prolong the courting process for in-game months without the content of the courting getting stale.
I wanto to be able to sire children in the game, to be able to watch them grow up, to be able to dynamically interact with them with near the same freedom that I would interact with a child in real life.
I want 100% completely interactive environments; If I cast a big enough fireball spell at a large city tower, I expect it to explode and collapse, and I expect the city to then have the AI and scripting to build another one (or to rebuild whatever I destroy in the game everywhere).
I want a combat system that is a state-of-the-art virtual fencing system, a magic system that provides me complete freedom (not just of spells, but of all powers, like the powers of Daedra lords or Psiijics, in full detail), and a stealth system that factors in all possible motion and 100% of all AI and environmental effects.
Etc, etc, etc.
This is me not keeping to Bethesda's resource plan. Sure, it all sounds nice. But all of these things are a ridiculous drain to resources, and for most, it should be obvious that suggesting them is a waste of time, because despite the fact that the technology is there, it cannot happen.
Much better games have been made with much less resources? Name me a game that provides the graphical complexity that Morrowind/Oblivion did, coupled with the sheer explorative scope of Morrowind/Oblivion, that provided far more in-depth mechanics without saluaging from something else within their game? Every game in the history of video games faces that. They come up with draft ideas that sound awesome, but they can only do so much. And so they try to fit in all that they can, cut those things that just aren't essential or even tertiary, and try to balance the necessary things as best they can.
Morrowind basically used the exact same combat mechanics as Daggerfall and Arena, with some 3D animations as tweaking. Morrowind also had a wide variety of weapons. Oblivion completely redesigned the mechanics of combat from the ground up, in relation to its predecessors. Oblivion also had a piteously small variety of weapons.
Possible scenario A: TES:V basically uses the exact same combat mechanics from Oblivion with some minor tweaking (greatly expanding on the combat AI packages to factor in for dynamic skill checks, for example). TES:V also has a wide variety of weapons.
Possible scenario B: TES:V completely redesigns the mechanics of combat from the ground up, in relation to Oblivion. TES:V also has a piteously small variety of weapons.
Now, does this exact reprecussion model have to hold? No; resources can be drained from anywhere in the game, not just weapon diversity. But applying this basic model to, say, improving stealth with Splinter-cell-esque mechanics as a goal to roughly shoot for, can easily result in the same resource-deprivation.
Which gets back, once again, to what I perceive as the difference between an FPS and an RPG. An FPS narrows the field of the player's play style, while providing far more complexity to that field. An RPG does not provide that complexity in return for a vast myriad of possible play styles. Finite resources at work; they can only be stretched in so many directions.