Should it matter? Rounded corners are obvious and ordinary. Does changing the diameter affect how useful it is? If you patent 0.505" diameter corners am I allowed to patent 0.515" if I can show it increases $METRIC?
If I sound argumentative it's not intentional, I know sometimes multiple questions in a row like that can be taken the wrong way.
It matters in as much as one of the functions of a design patent is to prevent confusion in the market. Like trademarks, design patents are intended to improve the signal-to-noise ratio in the free market so consumers can more easily determine the providence of goods and services.
The less providence can be quickly, reliably, and consistently determined by consumers, the weaker will be feedback mechanisms in the market. When knock-offs flood the market, the original company will have less incentive to manufacture products with better quality, longevity, or whatever characteristic is desirable in the market. That's because they capture fewer of the dollars consumers fork over for those differences.
It follows that there's nothing per se illogical about making such fine distinctions as fractions of an inch. What matters is if the distinction serves the purpose of make the product distinguishable in the market to the degree that optimizes the market function of design patents.
If I sound argumentative it's not intentional, I know sometimes multiple questions in a row like that can be taken the wrong way.