Here is a bit of history of how handlebars these days are almost all angled up.
In the old days, every single bike had handlebars that were the traditional round bar, and almost always, the flats where parrallel to the ground.
In about 95 or so, the new fangled ergo bars came about, with a kink early in the flats which then went flat to the hood clamps. Most bike shops still sold these bars with the last bit of the flats still parallel to the ground.
Pro's started using the new bars, but they found the 'flat part in the drops' was at such a wierd angle that they felt they had to angle their wrists forward just to hold the bar. Loss of power was the result as the riders couldn't pull on the bars in a proper fist/forearm grip.
So, they started angling the bars up by about 15 degrees, allowing the 'flat part in the drops' to be in a more natural, and powerful grip for the fist/forearm.
From there, everyone started copying them, because it was actually a better angle, even though it moved the drops further away, and the hoods slightly closer.
Then, bike shops started selling bikes with the ergo bars always angled up...
And then new riders, who preferred the shape of the old round bar, started copying the ergo bar guys...
20 years ago I was riding a round bar, and these days I still ride a round bar. All my bikes have the bars parallel to the ground. I have tried an ergo bar in the early days when the last flat bit was parallel to the ground, and it just felt absolutely awful for sprinting with in the drops.
When I sprint, I really get my hands up in the drops. It absolutely feels awesome for power through my back while braced with my arms in that position.
I also 'track sprint' in a way, even in road sprints, so when I sit down after the jump, and spin up the gear further, my forearms are parallel to the ground, and the back is flat. And even then i'm still pulling on the bars.
I'm glad the round bar is still around, but I too don't get why you would buy a round bar, then angle it up.
We now have compact bars, which kinda combine the two bar shapes. They actually don't look too bad, and are probably pretty effective for road racing and such.
Anyway, that's my history lesson for the day
Don't get me started on 'compact' frames...
20 years ago, the 'angled down to seattube' frames indicated it was a girls bike. lol