The dungeon isn't just easier for players. It's also noticeably easier for GM's. Each room is usually a unique experience. You almost never see dungeons consisting of the same type of room over and over again. Why would you do that to your players? It's boring.
Now let's take a look at our wilderness map. It's got a lot of the same sort of hexes right next to each other. To the west, we have lots and lots of savanna. In the east, it's lots and lots of jungle. In terms of geography this looks right. In terms of running a D&D adventure this looks like a nightmare. How in the world are you going to prevent this hex crawl from devolving into an endless repetition of "another two hexes of jungle"?
If you happen to be one of these amazingly creative types who can come up with interesting stuff on the spur of the moment, you've got no problem. This map plus some wandering monster tables should give you all you need to create interesting terrain and situations for your players to deal with. If that's not you, however, you might want more help. And you can give yourself all the help you need with more random tables!
Any day (but not night) where a random monster isn't encountered, or some other interesting terrain feature (like a village or river) isn't encountered, roll a d12 and consult the following table for the jungle:
2: More nothing.
3: Even more nothing.
4: Short cliff of obsidian, measuring 3d4 feet high and 1d4 miles long.
5: Elven ruins built around a circle of massive crystal menhirs. Any magic-user spells cast while standing inside the circle are treated as being cast by a magic-user or elf of 150% their level (round down). If the moon is full, then treat the spell as being cast by someone with twice the level of the caster.
6: Empty monster lair. Roll on the wandering monster to table to see the type of monster, then roll for its treasure as per normal. 1d6 x 10% of the rolled treasure is here. If the monster rolled is sentient, there may be traps.
7: Quicksand! Double movement penalties through one hex.
8: Ancient Goblin Burial Ground. If players search this area, they can collect 2d100 copper pieces, 1d100 silver pieces, and 10d100 gold pieces worth of jewelry every hour, for 1d4 hours. However, for every hour that they actually find something, there is a 1-in-4 chance that they will be assaulted by 1d100 goblin skeletons the following night.
9: PCs stumble across the corpse of a dead adventurer. The human died of disease and/or infected wounds. The corpse will have fairly standard adventuring gear, plus one random potion. There's a 1-in-6 chance the corpse was carrying a map of the area and that this map hasn't been completely destroyed by moisture. It will reveal 1d4 hexes in each direction from the current location (roll separately
for each direction).
10: Ancient Shrine. Roll randomly to determine the alignment of the deities the shrine was dedicated to. Clerics of compatible alignments who meditate or pray at this shrine will be able to cast an additional 1st level spell the next day. Clerics of the opposite alignment will have the next spell they cast with a random component behave as if the lowest possible number was rolled.
11: An especially monstrous tree. If the PCs scale the tree to its top (this will eat 3 hours for up and down) they can map out every surrounding hex.
12: PCs stumble across the entrance to a dungeon!