Hi.
Yes you are right. According to this new law it is illegal to organize gambling on the territory of Russia. The same includes but not limited to the means of internet and any other telecomunication servicies.
There was same situation on russian boards like we have here. But at the end pearlgaming is completely correct. This law effects only casinos. They can not operate in Russia.
And that is not a problem for the russian player to play in casino with russian language, but based in other country, you know what I mean.
Regarding motivation…
This law comes from mr. Lushkov (the meer of Moscow).
After some researches it came out that too much money is spent by young people in online casinos. the same came out to be a problem for their parents.
Also one very important fact.
For example in Moscow you can find a small casino or small slots and videopocker center near every Metro station. The same came out to be a real problem, many tragedies related to that, when old women or young people are wasting all their money there.
Moreover we are going to have President election, so… they are making actions 
The psychology is simple…. everyone say that casinos are bad… let us close them.
But at the same time smoking is also bad… I will be not supprised if it will be illegal soon, just 1 month prior President election lol