Comment by _RPL5_

My pet theory is that it takes more effort with a Russian keyboards to type the smiley face.

With English, you do "SHIFT + ;" for the colon and then "SHIFT+0" for the bracket. When I type it, I hold down SHIFT with my right pinkie, and hit ";" with my middle finger. I then outstretch my pointer to hit 0. It's mostly a single fluid motion.

With Russian, you have to engage two hands instead of one. We have more letters in our alphabet so the ";" key is occupied by "ж" (a "zh" sound as G in Gerome), and the colon gets moved to "SHIFT+5". So now, to make the colon you have to first find "5" on the keyboard with your left hand, while holding down SHIFT with your right. Then you have to disengage your left hand, and reach for the 0 with your right to make the bracket. Rather than do all that, you can just place ")" and the context is enough to understand it's a smile.

It could also just be tradition. My earliest memories of the Russian internet are from the late 1990s, and the convention of "))))" was already in place.