I'm guessing that GRE didn't feel that there was a need for FM broadcast, while Uniden felt that it didn't add much (if anything) to the cost, and was a nice addition. Just a marketing decision - and Uniden seems to be making the better ones.
As for quality - if you want to know where that twister is, and the scanner is the only thing you have with good batteries, who cares whether you can even recognize the announcer's voice? I don't care if I can't even tell gender. Stereo? I'll take mono, gravelly voice and noise - if it'll keep me from getting killed. When the storm's over I'll turn on the stereo and listen to good audio. That's why I have local stations programmed into my BCD396T and my VX-5s. Whatever works in an emergency.