@Tyaren - It may have something to do within development. Dengeki Bunko was published by Sega so hiring the same VA to perform another game is likely simple as 1 2 3, where as TN simply only obtained the rights to add them in DOA as guest characters with reused voice clips.
Why has Akira completely new voice samples here, whereas the voice samples of DOA 5 sound incredibly dated and compressed (for all of the Virtua Fighter cast)?