Horses/boats may serve several purposes in a UFT context:
1) Expanded inventory.
you said: Give Geralt a back pack, it doesn't run away or dies because of enemies.
By expanded I mean not only able to hold more regular items but also certain bulky items which Geralt simply wouldn't be able to carry around for extended periods. Example: statuettes.
2) Help you cross natural barriers otherwise insurmountable.
you said: Like what? What natural barrier will be insurmountable to Geralt's legs?
Come on, give me a break here.
Rapids, steep mountains, freezing waters, monster infected waters, you get the idea.
3) Mounted combat. While Geralt is more effective on foot, Some enemies might be more susceptible to mounted combat.
you said: I thought there wasn't going to be any in TW3.
Mounted combat is in. They said Geralt is generally more effective on foot. But if he were to fight hordes of giants or other hefty creatures, it's easy to see how a horse might be an advantage.
4) You get to places you've never been to before faster than by foot.
you said: This is true. But after the first time, you can fast travel.
Even SKyrim sets limits as to when you can fast travel. For example, You cannot fast travel during combat. So the point applies not only to places you've never been to but also when fast travel is disabled.
5) You get out of dangerous situations where you can't fast travel faster than by foot. That speedy horse or boat just might save your rear end.
you said: Not necessarily, you can dodge a bit and then fast travel. As I remember, enemies in the TW2 had boundaries to which they chased you.
Again, even Skyrim disables Fast travel during combat. You cannot fast travel during it. So indeed a speedy horse or a boat just might save your rear end. This alone would make horses and boats priceless. Enemy AI has been revamped. Let's hope they now chase you down much farther.
This post has been edited by Agent Blue: 14.03.2013 @ 23:30