How fun would that be, if you could fly to the top instead?
It's similar in wow, you avoid everything in the world, land on what you want, fly off again, I cannot understand how people don't see what it does to the world. You could go "don't use it if you don't want", well for starters that doesn't help the pvp department, and second, people will pretty much always do things the quick way even if they despise the quick way.
Sometimes people need limitations for their own good, they do not have the willpower to do things the hard way, even if the hard way would make it more enjoyable. You could get rid of travel alltogether and make a portal tab in your characterscreen, would that help the game? Some would argue it would, but I would disagree.
Limits aren't always a bad design choice.