The hunter tends to use two melee weapons because -if- she's dumping Str (which isn't a requirement), she's got powers that give her good hit bonuses with a single weapon in melee, but not a lot of powers that give her good hit bonuses when attacking with two weapons.
Of course, she still has Twin Strike, and she has powers like Commanding Confrontation that give her crazy damage bonuses. So even in melee, she may be better pulling two melee weapons and Twin Striking for all she's worth, particularly with a huge damage bonus, rather than making one attack that's somewhat (say, +5) more likely to hit.
OTOH, one nice thing about the Hunter build is that it gives you flexiblity. Against a brute who you hit on a 2? Switch to two weapons and hit on a 7 instead. Against a soldier who you hit on a 13? Get a ranged attack in or two, then switch to single-weapon melee, where it's easier to get combat advantage. If you pick a good weapon group (heavy blade, probably), you can have even get focus and expertise for two-handed weapons, thrown weapons, and off-hand weapons with the same feat if you want.