I really hope ESO becomes one of the best MMOs out there and stays true to Elders Scrolls experience. With that said, here are my suggestions to the development team at Zenimax:

World Bosses & Legendary Items: The developers should add world bosses to the game that have a chance to drop legendary items (e.g. Daedric Artifacts). These outdoor bosses are extremely rare and spawn at a random location. When a boss spawns, there is a zone-wide warning. To defeat, you require a well organized 12 man team. Imagine visiting a small town when all of a sudden you hear bone chilling laughter. You look off in the distance and see a powerful Lich roaming the countryside with his undead army.

Darkness is important for ESO: The developers really need to make nighttime and dungeons dark. Now I’m not talking about making it pitch black. People need to appreciate torches and spells like magelight. Attaching a small travel lantern to your character’s belt would be a cool feature.

Dueling & Inspecting: The developers need to add dueling to the game. Dueling allows players to get accustomed to PvPing and helps them practice for the Alliance War. This may even help get the die-hard PvE players out of their comfort zone and help with the war effort. For those players not interested in dueling, have the option to auto-decline any such request. Lastly, a player should be able to inspect another player’s equipment.

Character Sheet Background Story: The developers should consider allowing players to add a background story to their character sheet. Basically, a small text box would be displayed when other players look at your character sheet by inspecting (works with item 3 above). This allows you to feel more connected with your character, which ultimately increases immersion. People could write several basic facts about their character, or even write elaborate background story. This feature is for the role-players.

Unarmed Skill Line: The developers should add Unarmed Skill Line (Martial Arts Skill Line) to the game. These skills would be based upon stuns/disarming opponents as damage will be low. This would be a welcome addition.

Craft Cloaks: I’m hoping the developers add the ability to craft cloaks with varying styles and quality (cheap burlap to fine linen). Would be epic to show off your guild colors and/or symbols with your new cloak!

Rested Experience: The developers should add “rested experience” to the game, which slightly increases experience gained from exploration, killing mobs and completing quests temporally. You get the rested experience when you log-off from an inn and it slowly accumulates when you are away from the game. This gives casual gamers an extra incentive to log-in and play.

Character Origin & Birthsign: At the character creation screen, players will pick their Origin and Birthsign for their new character. This is for flavor only and does not affect gameplay. To pick Origin, players will choose from a list of home cities (based on chosen race). To pick Birthsign, players will choose from a list of constellations under which that character was born. Both Origin and Birthsign will be displayed on the character screen. Again, this is to add flavor. http://elderscrolls.wikia.com/wiki/Birthsign

Tamriel Holidays & Calendar: I’m hoping the developers add holidays according to the Tamriel Calendar (a calendar will be included in-game that shows holiday events and allows guilds to organize their own events/meetings; however, to stay true to the minimalist approach to the UI, the calendar can only be accessed while in a tavern). Taverns will become natural meeting spots for guilds. http://elderscrolls.wikia.com/wiki/Category:Holidays

The in-game calendar will show the 12 months according to TES lore, such as:

Morning Star
Sun’s Dawn
First Seed
Rain’s Hand
Second Seed
Mid Year
Sun’s Height
Last Seed
Heartfire
Frostfall
Sun’s Dusk
Evening Star
The in-game calendar will also show the 7 days according to TES lore, such as:

Morndas
Tirdas
Middas
Turdas
Fredas
Loredas
Sundas