Look for money. All serial producers in order to raise some money should follow some unofficial 'guidelines' otherwise TV channels (especially owned by federal government which means large auditory and large revenues) won't buy them.
Taking in view the catastrophic demographic situation in Russia, there is a policy for advertising of 'family values' (coming from the government). It is quite a normal situation when the plot gets corrected from time to time to reflect that.
Saying all that (even though I don't watch national TV channels at all) I doubt that this is a widespread tendency.