Mostly men wear these.
Having volunteered at a monastery, I;ve mostly seen these big beads worn by worker monks (of course, not the 108-strand which spans the whole body, but an 18 or 27 bead strand long enough to wear over the head but short enough that it can be stuffed into deep pockets.)
These are heavy duty beads, which don't break easily when a monk does construction, farming or wielding work. (compared to dainty pearls or crystals that could be crushed under pressure.)
I think it's meant to symbolize the "heaviness" of human suffering, etc.
Urgh, leave it to a middle-aged white guy to turn something into a tacky fashion statement. (Refering to the picture above... "Look at me, I'm wearing cool Asian-y outfits because I'm just sooooo unique....")
(Sorry! I know I'm being judgmental, I really shouldn't be!)