One factor is also that the current age groups are much smaller. The Ovechkin age group of 1985 is the biggest in Russian history (more babies were born in 1985 than ever before or after), but with birthrate collapsing in the 1990's the current age groups are something like 40-50% smaller.
On the other points, yes popularity is a lot yes, although I never lived in the USSR, I have only worked in Russia since around 2006. However they should still be more than capable of producing quality players. I personally really enjoyed how they played against the Swedes, and finishing let them down. It was the first time I enjoyed a Russia WJC team playing in North America. They were bad tonight against the USA and bad against the Czechs but hey it is junior hockey a lot of things can change. I don't think many expected Kucherov to have as many goals and more points than Ovechkin by 2014-15. He had talent but his production in the NHL jumped big time.
With regards, to birth rate, I don't think you can attribute birth rate to success (With regards to 1985) Russia's birth rate is now higher than the USA.
I think many here a few years ago expected a lot from the 1995 crop, but we will never know where they end up. They were great in the 2012 Under 17 challenge but a lot can change from 18-21 years of age. I am not completley against kids going to the CHL as long as they are placed in an environment which values their skill-set, and focuses on improving other aspects of their game while allowing creative freedom. It is there career, and they have a choice. However, you can't blame the system for them leaving. They want to play in the NHL, and they see no point playing in the MHL when they can be playing CHL in front of good crowds and increase their chances (So they believe) of playing in the NHL. The pulling power is too big and this will always be a problem unless you want the return of the USSR. Some players have become better players continuing their development in NA (Zadorov is a good example having 20+minutes per night, 1995 born). Remember Knyazev from the 2002 Gold medal team? captained a WJC Gold Medal team. Was also named best defenseman in the tournament, boom nothing. A lot can change quickly.
I still think we have to wait and see on the 1995 class, only a few years from now will we be able to see whether these kids are good.
What i mean is, have a look at the 2002 (Who lost to the Finns and Canadians before beating them in the medal games) and 2003 teams you mentioned, they "dominated" the WJC, who were the stars in those squads? Kovalchuk, Chistov, Knyazev, Svitov, Frolov, Perezhogin, Grigorenko, Trubachev(I may be missing players), but those were generally the top players on those two gold medal teams. These players had great skills but the majority of them never lived up to the "hype". I think 3 Russians went top 5 in the 2001 NHL Draft. Only one succeeded.
edit : Kovalchuk did not play in the Gold Medal winning side.
A lot can happen between the ages of 18-21.