I personally find it lamentable that so many people seemingly have operatic/soaring vocals as a requirement for prog music, and a lot of prospective bands then follow suit by sticking with a crappy operatic/soaring singer than rather having a good "normal" singer. (Haken, looking at you)
When I look at my favorite prog bands, (Genesis, Rush, Pink Floyd, Spock's Beard, OSI, Wilson etc), they all had "shit" vocals, but it never bothered me in the slightest. The opposite probably actually.