2. EASE OF TURNING IS AN ADDED BONUS
There is a bonus to the form on the left above. It is far easier to turn than the the flat-bottomed piece. The flat-bottomed piece has a tight radius at the transition from side to bottom on the inside. When rounding that bend, the shank of the gouge will “ground out” against the rim of the bowl and cause the bevel to come off the work, resulting in the loss of control of the cut. The bevel will only regain contact with the surface part way to the center so there will be a very rough cut from side to almost center. Add to that, a flat bottom is very hard to do well. Should you want this design (and there may be a very valid reason), the answer is to use a gouge with a very steep angle (say, 45 degrees at least). This will stand the tool straighter up, keeping the shank away from the rim at the transition from side to bottom.
Contrary to all this, the bowl with the simpler curve is much easier to turn, having a curved bottom and no issues with the shank of the tool coming in contact with the rim on it’s path around the curve. Additionally, there are no sudden changes in direction throughout the cut, only a smooth transition from rim to center.