I like trekking through the wilderness for one reason, and one reason only... So that XP can jump out of the bushes at me.
Really, there are some valid reasons to play out extended travel time... I can think of two, offhand.
1. To exposit upon the natural state of the world and changes to it. If you want to show your characters that the world is a dangerous place, that nature is powerful, that things are changing for the worst, or whatever... One of the best ways to do that is to stick them out in the world, preferrably far from any possible assistance, and trample them with the way that things are. Batter with a hurricane. Smash them with a stampede. Boil them with heat. Starve them with a drought. Break them with a tiger... and so on. You can go a long way towards setting the tone of a campaign by allowing your players to see how their characters interact with the forces of nature. If you make their first few wilderness excursions easy, they will understand that they operate above the laws of nature. If you make them difficult, they will understand that the laws of nature are powerful and not to be trifled with.
2. To explore the nature of the characters' dealing with themselves and each other. nothing can tell you more about the nature of your players and what they want out of a game than how they react when you tell them that a day (or a few days) of travel has gone by, and that it's time to make camp and (describe the scene, make it engaging, but non-threatening) ask them what they would like to do for the rest of their evening. It is often useful to toss an NPC or two into the mix when you do this. Have them hook up with some traveling salesmen or pilgrimaging ... pilgrims... or whatever. Give them some idea of the sorts of activities you are looking for (perhaps the pilgrim whittles wood), and see where they go with it. Tacticaling players will do tactical things... Immersing players will immerse... and so on. There will, of course, generally be some mixing and matching going on, but this is a pretty good tool for quickly figuring out what your players really want out of a game.
In general, though, unless you are looking to give your players an opportunity to do something specific (whether that be relaxing and interacting or accomplishing some more specific goal) or unless there is something that you want to demonstrate (the harshness of the wilderness, the presence of the divine, whatever) about your world... wilderness trekking should be kept to the minimum amount necessary to get your characters from point a to point b.
There is nothing that I hate more than listening to/watching a DM roll wilderness random encounter chances while saying, "time passes uneventfully... time passes uneventfully... time passes uneventfully..." you either have an encounter planned, or you don't. Let's get to the good stuff.
Later
silver