Introduction
The primary purpose of mounts in almost every game is to get from Point A to Point B in a shorter period of time than it would take if traveled by foot. This is true for some Elder Scroll games and MMO games. How they function and how they are used however are often times very different. As it has been mentioned that mounts will be in The Elder Scrolls Online, http://www.gamespot.com/the-elder-scrolls-online/videos/the-elder-scrolls-online-e3-2012-stage-demo-6380873/, we have not yet been informed on how they work. I'm hoping that mounts are added in a fun and natural way, although that could mean many things.

System Mounts in the Elder Scrolls Series
Mounts were included in the older Elder Scrolls games as well as Oblivion and Skyrim. In the most recent example of Skyrim, you would purchase a horse for a designated amount of gold and you'd ride it off into the sunset. The horse is another creature of the world however and is subject to the many dangers of Tamriel including bears, dragons, and gravity. If you were to dismount it, it would be free to wander about to get lost and jump heroically into the fray when you're fighting where'd it most likely just get in your way and die a horrible death. Horses were not always available as they could not enter major cities and if you couldn't find it, you couldn't use it.

Elder Scrolls mounts feel like part of the world, yet they are subject to negative aspects in the environment. They could be perceived as a tedious annoyance or just another challenging part of the living world of Tamriel.

System of Mounts in Modern MMO's
Mounts are a big part of many Modern MMO's. In notable examples Star Wars: The Old Republic, World of Warcraft, and Rift; they're invulnerable entities that you could summon whenever you're not in combat and in an outside environment. You'd wave your hands for two seconds and they automatically appear beneath your character from nowhere. How they're used is often you ride into combat, instantly dismount, kill some unlucky thing, flail around until you're out of combat, then mount up in 2 seconds and repeat the process.

MMO mounts are convinient and handy, yet they don't feel like part of the world. They could be perceived as a shallow game mechanic or a necessary item to get things done quicker.

System of Mounts in TESO
We have no information on how mounts will work in TESO. Will they be something to protect like in the Elder Scrolls? Or will they be a simple method of convinience like in many MMOs?

I feel like most players would be frustrated if their mounts could be lost forever for one reason or another. On the otherhand, I don't want to see the world of Tamriel be filled with just people on mounts who's only reason to be on foot is to kill something or go in a building for a minute. I'd like there to be more depth to TESO mounts than other MMOs. Take the http://www.youtube.com/watch?v=KxJTsq2XeKY&feature=youtu.be for example; the PvP siege battle towards the end would look a lot different. Instead of an army charging the walls and swarming into the keep; it'd be a bunch of horseman who want to get close as quickly as possible so they'd ride in and instantly dismount.

I'm hoping some sort of system could be developed that is a balance between Elder Scroll mounts and MMO mounts. The two main points I think are important to consider for this game are:

Point 1: The mount cannot be lost forever. I myself would be fine if I lost a valuable mount due to a fault of my own; but I know most people don't feel the same.
Point 2: The mount cannot be summoned instantly whenever you want. I'm aware this means traveling may take slightly longer depending on the circumstance; but I feel like this would preserve a "real and living" feeling to the game world.

What are your thoughts on the matter?

Short Version: Mechanics of Mounts in TESO should be useful but have depth.