Again, I suspect this falls under 'European thing' but nearly everybody I know texts to an extent. This includes my (retiree!) parents and first grader neighbour kids (toddler++) who I suspect text better than they write.
I believe you have misread something. The 4-5 RSD is the cost for 100KB (in US terms, a little over ~$1.3 for 1MB !). To add insult to injury, MTS's gprs/3g connections are notoriusly unreliable/slow, basically good for (small) emails but not much else.
It's a vicious circle though - we have a very little % of smartphones (price sensitive market), so GPRS is not widely used (and 3G even less) so the providers have little incentive to upgrade data services which lowers demand for smartphones further, circle complete.
EDIT: Disclaimer: I'm not a MTS customer