there are about a million of these threads in the skyrim section now.
im assuming when you say fast travel that you specifically mean oblivion/fallout 3 fast travel. i dont know many people that are opposed to fast travel period, just the method.
first off, in games like oblivion and fallout 3 ITS NOT OPTIONAL, ill repeat that cause some people just dont understand basic concepts of game design. oblivion style fast travel IS NOT OPTIONAL. the entire game is designed around the use of the fast travel mechanism considering the number of quests that send you from one side of the world to the other. most people do not want to walk all over the place for tedious quests especially if they have done them a zillion times before. however, oblivions system is essentially a cheat.
1- it has no cost whatsoever
2- there is no risk whatsoever
3-its very easy to exploit to get you out of trouble........in STALKER, if i use up my last medical kit and im low on health and ammo i have to survive long enough to get back to civilization or hope i stumble across a stalker that will take me there for a fee. this is not the case in oblivion. if i use my last magicka potion and last health potion and my gear is worn down and have no repair hammers...............it doesnt matter cause all i do is click on my map and TADA im back safely in town. no threat whatsoever.
4-oblivion/fallout are actually in the minority with their method. DAO gives you an overhead map where you almost always get a random encounter. two worlds 2 and the witcher use teleporter stones which you have to actually travel to in order to use. even with just cause 2 you have to pay for the black market to take you somewhere.
a simple fix would be to do it like daggerfall did it. have a cost and a possibility of a random encounter if you choose to use it. even better would be a system that uses both of them. i havent played it myself but supposedly red dead redemption has both methods involved.
as for morrowinds system.....as another poster pointed out you were never more than 30 seconds to a minute away from travel services except for a couple of waaaay out of the way quests. i put people that had problems with morrowinds travel service in the same group as people that couldnt follow simple, written directions and have to use a big arrow to show them where everything is.