simple process of elimination
there only two combat related button, one to attack with a weapon and one to aim/block with a weapon.
and since both attacking and aiming with a throwing spear it makes sense there is no button left for two form of attack.
And I doubt they make a function exclusive to VATS, since not everyone enjoys using VATS and so it be unfair to them.
I'm sure they could figure something out.
Anyway, the only thing that makes being a melee character in Fallout 3 slightly difficult is stealth (or lack thereof). unless you use a stealth boy, you *might* be able to get off one good kill without being detected, but as soon as that one dies, if there are any others near by, you're detected, and no more of those oh-so-important sneak attack crits.
So there you are, standing in the middle of 3 guys in power armor, just swinging away, hoping you can land a paralizing palm with your next VATS attack...
I hope they give melee characters some kind of better stealth perks, because without stealth, melee is pretty tough. I mean, running in fists a' blazin' isn't really a viable option unless you're high enough level to take a lot of hits.
But I still love melee. I have made a few Melee/unarmed characters in FO3, and whilst it's a bit tedious having to run up to every enemy, it's also pretty fun. I also use a scoped .44 magnum for times when closing the gap would take too much work. unfortunately, ammo for the magnum is limited.
Then again, small guns is just too damn easy. I'm pretty excited about these changes in New Vegas. I think playing unarmed/melee is a great way to add a new dynamic into the game