i think its only fair to give an advantage to BTCD holders as they have been with the project for way longer than ICO investors. They are like super early investor when a company is running out of the garage.
That's probably true for some holders, yet there are current holders, who bought BTCD when the ICO started, and/or who are buying now to benefit from the bonus. Fairness might be irrelevant here and shouldn't be an issue as the rules were layed out from the begining.