I just had another thought: Since you remain in connection with your memory throughout a WILD, you stand a better chance of hanging onto that access after the transition to the dream (only a better chance, though, because your sleep systems are still set to switch off that access). Perhaps this better chance of retaining memory -- and the acompanying higher-quality LD -- in a WILD is the real reason people think WILD is "better" than DILD? So the special thing about a WILD might not be that you never fall asleep, but that you never lose memory. Hmm.

Probably not, but just a thought.