What bothered me about the Rick Dees shows, especially those between 1993 and 1995, was that he wouldn't play many rap songs, even if they had radio friendly versions (with the profanity removed) on his countdown shows. He would note the songs and their current positions and move on to the next song.
This was different from Casey Kasem, who, at that time, was using the same source (Radio & Records) for his shows. He would play the rap songs that Rick Dees wouldn't play.
I think it was in 1996 that Rick Dees finally began playing some of the harder edged rap songs that charted. What he did, and it is still done today, was to record two different versions of his shows, one for top-40 stations and one for hot AC stations.
Regarding his voice, very few disc jockeys have managed to retain their voices into old age. Steve Goddard's voice is still (relatively) unscathed and so is the voice of Wink Martindale who is now in his 90s. At the time of his passing, Charlie Tuna still sounded pretty much how he sounded like in the early 1970s when he was on KHJ--but they were the exceptions, not the rule.