A number of applications require having a dry feel to them. The feel of a formulation often has been associated with volatility. Volatility is the ability of the compound to evaporate under the temperatures at which it is used in formulation.
For cosmetic products, this temperature is ambient. D4 evaporates at room temperature by about 50% in 7.5 hr but D5 is much less volatile, showing a loss of only about 4.5% in 7.5 hr. D5 provides a dry feel but is not appreciably volatile at use temperatures.