This is an excerpt from Todd Howard's 40-minute talk at DICE 2012 about Bethesda's development process and miscellaneous Skyrim trivia.
I found the whole thing quite interesting - you can watch it here on Gamespot's channel:
Anyway, this video just shows a few minutes from the middle - the aftermath of the "Game Jam". Awesome stuff!
Of course, since then we've already received a lot of these features through patches - ranged/magic killcams and underwater effects, for example. Dawnguard also adds flying vampire lords, perk trees for vampirism and lycanthropy, and crossbows (among other things).
Note that the features shown in this video were developed AFTER Skyrim's release, so you can't claim they "left them out" because of greediness or anything.
UPDATE: I thought I might as well link to features added in by modders (that aren't already added through DLC or patches), so here we go: (if you know any other great mods that do these things then feel free to post me a link)
KEY: () - unimplemented; (x) - implemented by Bethesda in patches or DLC; (m) - implemented by modders
• () Seasonal foliage
• (m) Flow based water shader - the "WATER" mod is probably the best for this (http://skyrim.nexusmods.com/mods/13268) - it includes a "get wet" effect and wet rocks as well as rivers flowing in the correct directions
• () Spears as weapons with a new animation system
• (x) Kill cams for ranged combat and magic - added by patches
• (m) New stealth options like water arrows and assassinations - water arrows: http://skyrim.nexusmods.com/mods/22234
• () Guards relight areas
• (m) Paralysis runes - included with Midas Magic: http://skyrim.nexusmods.com/mods/3413
• () Moving platforms and hanging structures in dungeons - there are moving structures in Apocrypha in Dragonborn DLC
• (x) Water currents in dungeons - included with Dawnguard
• (m) Dark dungeons - sooo many of these - try "Realistic Lighting" or an ENB profile; though you might have difficulty getting dark dungeons without getting pitch-black nights as well
• () New companion options
• (x) Build your own home from scratch - included with Hearthfire
• (x) Adopt children - included with Hearthfire
• () Skeletal butler - Dremora Butler with Dragonborn DLC
• (m) Combine magic to create new attacks - well... I recommend the awesome Apocalypse Spell Package , which provides so many unique and interesting spells you're bound to find some epic combos: http://skyrim.nexusmods.com/mods/16225
• (x) Goblin enemies - with Dragonborn DLC (Rieklings)
• (x) 'Way Gate' fast travel - included with Dawnguard
• (x) Epic mounts like a flaming horse - (arguably) included with Dawnguard
• (x) Mounted combat on horses - added by patches
• (x) Dragon mounts - with Dragonborn DLC
• () 'Soul bug' familiar
• (x) Kinect-enabled 'shouts' - added by patches, or by mods for PC (I recommend http://skyrim.nexusmods.com/mods/5626/ with http://skyrim.nexusmods.com/mods/32821/)
• (x) Screen space ambient occlusion - available through Nvidia graphics profiles
• (x) Enhanced underwater visuals - added by patches
• (m) Footprints in the snow - The only footprints mod you'll ever need: http://skyrim.nexusmods.com/mods/22745/
• () Verlet surfaces for non-rigid objects
• (m) Ice and fire arrows - could try Arrows of Magicka: http://skyrim.nexusmods.com/mods/9799
• (x) Werebears! - with Dragonborn DLC
• (x) Lycanthropy-specific (werewolf) skill tree - included with Dawnguard
• (x) Become a flying Vampire Lord - included with Dawnguard
• () New Vampire imp minions
• () Mudcrab animation tweaks
• () Giant Mudcrab enemy - one day...
Cheers to Joystiq for the original feature list.