Oh boy.
I could go on forever about various theories I have about this.
For one, I think that there’s a general trend in music of drifting away from the loud, full-voiced singers of the past (who had actual tone, and vocal training) and towards newer types of vocals, often with more unconventional sounds. This is part of the overall fragmentation of rock music and its divergence into many different paths, so many that it’s impossible to classify “indie” music anymore because the label is now meaningless and basically only says that the music in question isn’t played on mainstream radio (and even that is not always the case.)
I think that a lot of rock people (the kind who are deeply into their music) started, probably sometime in the 80s, to associate big, loud, full voices with (what they saw as) egotistical, cocky, showmanship-like rock, like glam and 80s pop, and got sick of it, and wanted something that was more introspective, emotional, and less produced-sounding. This is what led to grunge, and the massive amount of alternative rock that was going on in the 90s but has only recently gained widespread recognition, like Modest Mouse (which formed in 1993) to name just one example. Comparing the kind of voices in 90s music and the kind of voices in 80s music, it’s apparent that the “big and full” voices gave way to quirkier, less conventional ones.
This trend continues to this day, especially in “indie rock” (as I said, a meaningless label in theory but a good term for "non-mainstream-radio-music in practice) - that big, full voice is just not in vogue anymore.
There are plenty of new singers who can really belt it out (like Brian Aubert of Silversun Pickups who sounds like Billy Corgan’s brother) but they’re not belting out with the kind of tone and clarity that I get the sense the OP wants.
Hey, music changes all the time. Like I say, you don’t like it, start a band. I did it and it’s working out great.