I read comments of people who claimed pretty much the opposite, though. There even was an "Alternate voice acting for Derelict"(or similar) thread somewhere.
We will not replace all voices, though...only the ones in dire need of replacement.
What you fail to mention is that that thread contained any number of responses completely decrying the suggestion. As Droid803 stated, there will always be people out there who don't like some particular upgrade or another. These people, however, rarely constitute anything close to a majority. As I said before, completely discounting consideration of my own performance (and I'd probably be overly-critical of my own voice, if anything), I greatly enjoyed the vast majority of the work that went into Derelict. All of the main roles had well-defined and memorable tones, and all of the lines are adequately audible. Considering we're all a bunch of complete amateurs with (mostly) crappy old mics doing this, results like that are about the best that one could hope for.
I was (obviously) involved with the process of Blaise Russell organizing the voicework for Derelict, and I saw how long it took and how much of a hassle it was to try to get everyone's lines submitted. Hell, I know how ridiculously long it's been taking me to get anything in for my part in Warzone (I swear I'll get back on that this week at some point). It's hard enough to do all of that once, and at least in my mind, there's absolutely no reason whatsoever for it to be attempted a second time for a campaign with already-complete voicework, if for no other reason than the fact that it nullifies the hard work that the original actors contributed. Getting myself or one of the other actors to tweak a line or two that didn't come out right is fine, but completely replacing certain roles just because one feels like they can seems like so much wankery.
What I know right now is that I can play through Derelict on a SCP build with no visible bugs and a full voice cast. As far as I'm concerned, the restoration has already taken place.