True, Bruce's voice has definitely aged considerably. I remember how some of the later Trek video games, like Legacy, had all the captains' voices, and TOS-Kirk (who was supposed to be mid-30's) sounded way too aged-70's Shatner. Stewart's voice has also gotten quite frail sounding in recent years compared to TNG-Picard. So yeah, it's a drawback. Although there are new technologies now, like
MorphVOX, but more sophisticated, that are able to re-tune someone's voice to sound like another's with a sample of that other person's waveform. It might not be too difficult any more to use advanced signal processing tech to make people's voices sound "younger" by smoothing them out, much like a CG algorithm smooths the lines on someone's face, visually. Probably easier to do that than change the voice entirely.
The advancements in digital tech have really made it so you don't really need a high-paid actor to do the job. Once you have the meshes and wave-forms, you can have someone say and do anything you want. It has all the Hollywood types freaking out - and rightfully so - how they might be conceivably usurped by digital reproductions from studios who own their
characters' likenesses. The Rogue One movie put into perspective how actors will be used after death, and forcing actors to rethink how future contracts are going to be written, specifying how their likenesses would be used (or not) by the studios postmortem. It really is a strange time to be alive right now...
