Harley probably never really considered the vast number of different body types riding their bikes and developed a bar that fits a limited few OR they knew it wouldn't work for most hoping they would swap them out for other HD bars thereby making more money for the company.
Stock RK bars blow

 

I hardly ever change things out after I settle on a bike but mine came off about six weeks after it came home. Had to lean way too far forward to be comfy.

 

Short answer....everything.

 

^^we have a winner!

 

Here's a before/after photo. Stock bars/Heritage style bars.

You can see how far back and up the Heritage bars come in the top right corner. The Heritage bars felt great but I didn't like the way they looked so now I've got 12" apes. SEE BELOW

 

Nothing is wrong with the bars, it's your body doesn't fit the bike

 

Gotta tell ya. Rode stock rkc bars for 2500 miles. Pains in wrists, neck and shoulders. Put on heritage style bars this winter and huge difference. Not perfect. I still need to adjust the angle a bit but 90% better than stock. I'm only 5'9" and with stock bars I was hunched forward and down. Heritage bars straightened my back and got rid of the pain. Not a lot of miles so far but much better driving position. Another noteworthy mod was a LePera continental seat. Love the firmness and slightly farther back seating position. No more nuts on the tank.

 

Others have pretty well explained the poor position provided to most, I didn't like the constant use of the push up muscles because of the leaning forward position. On all my previous machines I could lean back and "hang on" which also seems to stabilize the steering. It was no quick decision, kept the factory bars for a year and made several trips which included 700+ mile days. No serious discomfort issues, but they just weren't "right". The Heritage style bars are not perfect but close enough that I have no desire to experiment any more. Should say, this is an 08 Road King, I'm 5' 11" and wear shirts with 34 inch sleeves. Perhaps if my knuckles had dragged on the floor when I walked, the factory bars would have been great.

 

fine here, but I have 34" sleeves so long arms. kind of like blonds, brunetts, and little butt gals! We all have our likes and dislikes.

 

Hey. I like big hoots. Little hoots. Big butts. Little butts. All things considered I'm pretty easy to please in that area. Wait. That's off topic. Uh.... Um Harley.. Uhhhh WHATEVER