The Hobbit: Why all the dwarves?

We all know the set up; Thorin and Co. enlist Bilbo as the lucky 14th member of their party.  Plus, they wisely foresaw the value of a sneaky guy in procuring a treasure hoard.  But why exactly were there so many dwarves?

In order of appearance, here is the roster of Dwarves and their primary contribution to the adventure:  

Dwalin--The first dwarf to arrive at Bilbo's house, he is the first dwarf to arrive at Bilbo's house.
Balin--Dwalin's brother, he is the oldest and wisest of the dwarves.  He is also their go to look-out man.
Kili and Fili--Twins, they are the youthful ones. They are good for doing any dirty work that required strong arms and sharp eyes--except being the lookout, which was old man Balin's job. 
Dori--On his shoulders fell the responsibility of carrying Bilbo whenever the hobbit was unable to keep up with the pack or climb a tree or grab an eagle.
Nori--There is no evidence to support the existence of Nori.
Ori--Conspired to gain a double share of treasure by occasionally speaking in a funny voice whilst wearing a Nori mask.
Oin and Gloin--Cousins to Balin and Dwalin, they carried the tinderboxes. 
Bifur--Kept Bofur company
Bofur--See Bifur
Bombur--Fat and weak-willed; he sleeps a lot, needs to be hoisted on occasion, and is manipulated into assisting Bilbo's plot to betray Thorin.
Thorin--Ostensibly the leader of the venture, in reality he always defers to Gandalf or, in the wizard's absence, relies on Bilbo to solve any problems that arise.

So we see, here are the tasks performed by the 13 dwarves:

• Arriving at Bilbo's house
• Performing lookout duties
• General labo(u)r
• Hoisting slow hobbits
• Pilfering extra shares of gold
• Lighting fires
• Providing stimulating company
• Obstructing progress
• Ordering Bilbo around

Did we really need 13 dwarves to do all this? Seems like instead of adding one hobbit to avoid unlucky thirteen, they could have dropped 5 or 6 dwarves and avoided the whole triskadekaphobia matter entirely.